It's not cheaply made - of course you can probably smash any BB if you want to. We've had no problems with 7100t quality and we've had them since September 30th.
7100: smaller form factor. Brighter, more vibrant screen, speakerphone. It's designed as a phone. If you are voice dominant (as opposed to e-mail dominant) this is the phone for you. Cons: screen washes out in bright daylight. Suretype takes some getting used to. Shortcuts form home screen do not work - it's designed as a phone first. BB second.
7290: Screen does not wash out in daylight. No speakerphone. "Classic" BB keyboard. Dual stage backlighting.
If you are mostly getting this for the phone, consider the 7100. If you are getting this for data/e-mail, get a 7290.