According to House of Hermes: Societas, its very much a suitable spell. In fact, its one of the sample spells favoured by House Flambeau for building endurance to pain.
However, it does somewhat violate the opiginal ArM5 intentions regarding Circle/Ring, which if I recall (Serf's Parma) were intended to be used only in conjunction with one another and was supposed to effect things within the circle.
For example, CrTe Circles just don't make sense. How much stone fills into the circle? The big problem is determining the "height" limit for the circle.
To be fair, though, this is not a problem that is solved by other Techniques. How far up does a MutoAquam(Auram) circle that turns all water and rain to wine work? If drawn out of doors, will it change clouds above it to rain? What about RegoAnimal spells that put animals coming in it to sleep. Would a bird flying far, far overhead drop from the sky in sudden death-nap of doom?
If I were SG-ing, I'd allow for Creo circles only for undifferentiable matter (Ignem, Aquam, Auram) but not for solids of any kind (terram, Herbam or, gag, Animal)
I'd also introduce Size motifiers for all of the above. For example, to have a circle with flames maybe a foot high would use RAW guidelines. To have the flames human-size, I'd demand +1 or +2 size.
But I do think that Creo circles are just way too fun not to have. They make for great baths, too. Creo(Rego)Aquam to make a spiral or water from ground to cieling indoors, which washes you off, but leaves you dry when you step out. Dirty water disappears when you break the circle. Perfect.
Also great for laundry.