We own a 2007 Dodge Grand Caravan SXT. Pretty much the same car as the T&C, with the exception of the trim packages. We love it, and haven't had any problems besides a small electrical issue with the power sliding door.
Keep in mind that the 2008 model year was the first year Dodge/Chrysler switched to the newer, more angular/boxy body style. As with any new design, the company has worked out many of the minor kinks (mostly fit and finish issues, not so much mechanical) with the introduction of the '09 and '10 model years.
One question to DEFINITELY ask your dealer, especially with pre-owned minivans, is where the car came from. Was it a private lease, or was it a "program car"? A lot of pre-owned mini-vans that are around 2 years old or so are coming off of a rental assignment. Dealers use the term "program car" as a blanket statement to cover rental companies, limo use, corporate use, etc. Try to determine the prior use of the car, as that may impact your decision. (I know my right foot has a tendancy to be a little heavier in a rental car, as are many others'....and I think many people would agree that you don't pamper rental cars quite the same way you do your own)
If it is a program car, be sure to take extended warranties that cover beyond the manufacturer's standard coverage. If the dealership won't offer it to you, don't buy from them.