Ok, I think that with the spoilers Erik so graciously provided, a bit of comparison can already be made with the old Mysteries system.
We already knew (from HoH:MC) that the general system for Mystery initation was going to be a massive improvement, making mastery of one or more mysteries a viable and easily customizable career choice for a magus instead of the impossible burden of raking unbelievable amounts of Flaws.
Also the setup of the various mystery paths or schools (yes, I know there're no longer rigid tree-like initiation schemes for the various virtue groups, but they can be freely customizble both by the various mystery cults and by individual mystagogues, and by self-initiaties, and that's quite nice) look like a definite improvement.
The old Hermetic Alchemy, Theurgy, and Numerology now give defined and specific game bonuses that are in-theme with the mystery concept, instead of the dreaded "in doubt, throw an Affinity at it" mechanic that plagued Mysteries 1st ed. It seems gone, and that's reassuring.
Alchemy has lost the bizarre variations to Muto, and the Elixir now sounds like a real improvement to vanilla longevity rituals. Alchemy still looks like the lab rat Mystery, with little or no "field magic" benefit to the traveling or questing mage.
As a general note, Mystery Virtues seem to have been compacted, so that in most cases it will be unfeasible to structure a Mystery cult "typical" iniation path around just one school (with the possible exception of Alchemy and Theurgy/Spirit Magic: I'm somehow perplexed about the wisdom of splitting the latter into two separate school), but most cults will lijkely mix and match from different areas.
For Alchemy 5-7 (depending on whether you count minor and major versions of the same virtue as separate) Virtues are reported. Hermetic Alchemy allows to plug an annoying hole in mainstream Hermetic theory and nicely sidestep the Limit of Vis by extracting non-Vim vis. I can see this rather popular with the average magus, since questing for gathering specific vis qualities can become rather boring after a while: this can be a meanace to the trading privileges of the Mercere, though. Vulgar Alchemy and Planetary Magic are mostly for the lab rat specialist, but they offer hefty bonuses in that area. I admit I did not understood the spoiler on Philosophical Alchmy to adjudicate its scope. Given its previous version was rather confusing and useless, I cannot but expect an improvement. The Elixir virtue again has strong appeal to all types of wizards and looks like a sharp improvement to the previous version (which appeared much hype, but lacked much of real long-term substance). It will be much interesting to compare the various immortality solutions that different Mysteries provide, from the Elixir to Becoming to, I expect, Spirit version of Becoming, Living Ghost or somesuch).
Talismans: this is an area that was wholly undeveloped in old Mysteries, but it is also a field where it makes sense that hermetic mystagogues have done some serious research. If I understand it correctly, Talisman virtues allow similar Muto Vim bonuses to thematic spells, and it is always good to see that heremtic research have been creative enough to develop a similar end result through wholly-different methods. It's laso good to have ways for different character concepts and magical specializations to be able to reap the same benefit without forcing the concept.
Astrology: this is another area where a lot of improvement in clarity (and easiness of use) of virtues has been done. Some of the old abilities (improved charged devices, horoscope bonuses to lab activity) are back, some are not. I must admit I miss the ability to establish an Arcane Connection by horoscope and to use specific astrlogical conditions as a substitute for ritual vis requirements. As much as these abilities were indeed prone to abuse, it was definitely nice to have Mysteries that were able to break or sidestep some limitations of mainstream Hermetic magic in thematic ways. It proved that Hermetic theory had definite potential for improvement. Oh, well. It looks like Alchemy virtues (and maybe augury/divination ones) will have to fulfill that role.
Nonetheless, Celestial Magic still look a quite tantalizing prize for an initation quest, with several definite bonuses to magical practice. Horoscope bonuses to lab activity, astrological cyclic magic for items, astrological durations, horoscope bonuses to spells, oh my !! Even if this looks like especially attractive to lab specialists, I expect Astrological durations and horoscope spell bonuses to be appealing to all kinds of magi. It will be interesting to compare Astrological durations with what is privided by the Spell Timing virtue. Is it another case of parallel development from different schools of hermetic research. In any case, astrology was a big component of Middle Age magic, and this virtue aptly reflect this importance.
Theurgy: this is my preferred mystery area, so my judgement may be biased. Of course, full judgement has to wait for the spoilers on spirit magic, too, since IMO theurgy and spirit magic mostly form two interwined halves of the same magic school (with the partial exception of Synthemata, which is really the other half of the sympathetic magic school, together with the Merinita Folk Magic path) and I'm perplexed about the choice to separate them. This is another area that formed a major part of Middle Age magic, so it is nice to see its ArM counterpat has the importance it deserves. In some ways, this is the polar opposite to Alchemy, as theurgy appears of greater appeal to the traveling or questing maga.
Hermetic theurgy is a quite nice and very thematic way for hermetic magic to improve its efficacy at flexible and spontaneous magic (esp. for those magi and Houses who are extraneous or hostile at druidic- or fae-influenced magic) and I expect this Virtue to show up in lots of initation paths. A lot of improvement about the old annoying "affinity something" version. Kudos to the authors for bringing back the old, very nice, Thaumaturgy concept, in a less godlike power version.
Names of Power and Invocation Magic: if I correctly understand this, it is a way to use the power of godlike spirit archetypes for bestowing focus-like spell bonuses to hermetic magic in a flexible way (I expect something like mastering the secret name of Vulcanus for craft magic, Apollo for healing magic, and so on). Another nice, thematic way to break the limitations of mainstream Hermetic magic at Muto Vis. Again, nice to see proof that hermetic magic has thematic potential for improvement. I expect this to be popular with all kinds of mages (the ones that won't use Talismans or horoscope boosts).
Synthemata virtues: sympathetic magic with a big oomph. Nice to see that the logical extension of sympathetic magic rules in mainstream hermetic magic are developed to their logical potential. In many ways, this is both the parallel and the complement to what merinita mystagogue researchers have done with their charm magic school. Less widespread in scope (as it only applies to creatures with a Might score) but nonetheless much, much appealing to many kinds of hermetic mages, from Quaesitors to demon-hunters to Merinita to spirit-summoners. I especially expect demon-hunters to go begging on their knees for being initiated in these virtues 
Numerology: here we have the previous read-headed Cinderella of Mysteries, the school which was cut out of the book for fanzine exile, with the exception of the Sacred Architecture bit, probably because the previous system was largely unplayable. Again, nice to see that a very thematic area of Middle Age magic was given a playable and appealing version in Hermetic magic. Hermetic numerology has its definite appeal for those subtle scholar types that wish to have all kinds of low-key quiet magic readily at hand, without the chore of painstakingly mastering each spell multiple times. Again, a nice, thematic way for break out of some limitations of hermetic magic system. Proably very popular for Jerbitons.
Hermetic Geometry: very, very nice set of target/range/duration. I expect the virtue to be especially appealing to summoners and demon/creature hunters (and diabolists), since the ability to cast Circle/Ring spells at range is quite useful for them. Another nice, thematic expansion of hermetic magic system, and a cool (and logical) way to incorporate all those old scenes of demons and magical beasties trapped in a magical circle in ArM.
Hermetic Architecture: Always nice to see that Bonisagus' accomplishments are not the be-all, end-all of magic, and hermetic mages can indeed manipulate regios and auras (but not set them up, alas). This virtue provides a clever solution to the old puzzle of how Hermetic mages were expected to be able and enchant very large structures, too. I expect it to be equally appealing to mages to wish to set up shop amid the mundanes and to the ones who wish to shun contact with them.
Review of spoilers end here, while I expect news about spirit magic, dream magic, and augury/divination, and for the book to slowly 
worm its way to Europe.
