Depends on who you are fighting against I guess.
With the trip against a mook, what are you really wanting to achieve? If you want to just knock him on the floor for a couple of seconds then...well he's going to get up.
But the difference is you get to decide how you take him out.
Don't want to damage/kill him? Got a good result? - then the trip easily could send him off his feet falling backwards ass first into a conveniently placed barrel where he is stuck until the end of the fight. Or more simply, he falls on his head and is knocked out for the rest of the fight.
Against a non-mook bad guy?
Well again, it depends on what you wish to achieve.
Usually there are more than on PC trying to attack the big bad - in this case then tripping him so it costs an extra shot (or do a stunt at -3, maybe 2 extra shots before he can act) then that might be just the time that your spell casting buddy needs to pull off a "banish" spell, or your high damage bruiser needs to run over from dealing with mooks to stomp on the guys head.
Remember, if you're not going for an effect that would do more damage, or give you some sort of advantage later on then there's no need to apply stunt penalty either.
i.e you can do more than just trip someone in one go if you were thinking you were only tripping him to set up your next attack
I punch mook in face, it hits, he goes down
is the same as
I trip the guy off his feet, he lands hard and as he flips himself back up I jump spin kick him in the head knocking him into a box of rotting veg.
As they both have the same effect - 1 mook out - then there's no extra penalty. Plus, you add the descriptive fun of the scene.