I compared both but keep in mind I am a total novice, I went w/ the 7290. I wanted blackberry to be what it was best at. I like form to follow function. The 7290 fit me best and I have grown quite fond of it.
just my .02
About a year ago my first Blackberry was a 7100t. I really didn't like the keypad and switch to the 7290. I've definitely been much happier since then. It all depends on whether you think the differences are worthwhile.
Get the 7100 if you primarily use the BB as a phone and want to read email. If you want to use your BB as a data device (read and create a lot of emails) and also have a built in cell phone, get the 7290.