As a Cubs AND Marlins fan, I suppose I have a bit more opinion about this trade than some others might, but overall it's a little foggy as to whether it'll be a good thing or not.
We'll start with the good:
YES, Todd Wellemeyer has major league experience.
YES, the Marlins only had to give up 2 "A-ballers" to get him, which isn't a terrribly bad trade.
YES, he's tall-ish.
Now, for the not-so-good:
YES, he really does have a career 6.19 ERA (although it's only over 57 appearances)
NO, he really isn't any better as a starter than he is as a long man out of the 'pen.
YES, he's got good "stuff," that ambiguous trait that managers love to talk about but which seems to really just make them overuse marginally talented players.
YES, he's part of a trade with the Cubs, which means they probably got the better end of the deal... =)
Honestly, though, Welly is not a bad pitcher, and has had (brief) flashes of excellence, but is for the most part painfully inconsistent. He does seem to be a hit with the ladies, though, so maybe that's something.
Still, I'm hoping he tears up for the Marlins anyway!