I have both. Bought the TF a week ago.. then yesterday used the 100 off at Staples, because when comparing them in the store last week, the TF's price sold me more than the anything else. I decided to get the SGT and compare. I may be very reluctantly returning the Transformer. I actually like the Transformer quite a bit more. And the SGT 10.1 GM just has some funky quirks that just sit wrong with me (such as the screen brightness, its ALL over the place, Kies? i HATE it. And well, there's samsung support :/)
However, the big issue for me on the TF is accessories. Sure, they pushed out the keyboard dock and called it a day. If you dont want that beast of an add on (cost and weight), then you've got to have faith that the mythical USB and SD dongles will appear next month. While there are some cases, there's clearly a difference between the SGT and TF.. the SGT is getting much more attention when it comes to cases and covers.
but MOST important, I'm really turned off by the lack of charging options (No pun intended) LOL. First off, it's just plain impossible to find a charging cable. All these TF's in retail and NOTHING. ANYWHERE. Thats really unbelievable. And no hint of a car charging option coming for the TF. Using DC-AC in the car is really a last resort.
the SGT happily charges from it's AC USB and USB connector with a USB extension cable, allowing me to use it and charge it in a reasonable convenient manner. Unlike the TF. Cables are reasonably easy to find for the SGT, and seem to run about 1/2 the cost of the TF OEM. Also OEM car chargers are available. (yeah, I know its just 12v, but still OEM is OEM, sometimes it's nice not to have to DIY your own cables).
I will say, one knock on the SGT for having a 'travel charger' without retractable AC prongs. But that feels minor compared to the TF charging conundrum.
Oh, do like the LED flash on the SGT. it works. and takes useable pics indoors. Not impressive, but acceptable. Not so much on the TF. Not sure I'd ever use the rear camera though. Not a fan of Samsung's changes to the camera UI, but thats minor.
Anyway, I'm really torn on returning the TF. If I could source some accessories and had firm ship dates on the TF SD and USB kits, I might wait it out and take the SGT back instead.