We just moved up to a TT from a pop-up this year. We had our 1997 Coleman pop-up for 4 years. Among the pros: A lot of bang for the buck. We had a 12' box with king sized bunks on each end - a pretty big pop-up. We bought it new for $5,300. We took very good care of it and sold it used for $4,000. It was very comfortable for our family of 3. Easy to set up and a lot of fun. It was a significant jump up from the tent we were in for 4 years before that. We looked at a lot of them and really liked the Coleman best. Coleman's tent material - called Sunbrella - is the best out there, in my opinion. Never leaked any water, and stayed new looking. The older vinyl or canvas tent materials aren't as nice. Other little things and big things made Coleman stand out to us.
The downside is the set-up. Can be a hassle if the weather's bad either during set-up or take-down. A long trip like the one we took to CA this June in the TT would have been much more tiring as we drove for 5 days across the US. It would have been a lot of set up and packing/unpacking for each night in a different state. The TT was really nice for that trip.
Also, getting ready requires opening it up to pack and unpack. The TT is easy in and out anytime. The pop-up is more work. But they are great, and a nice one can be had for reasonable money. Also easy to pull - with the right vehicle. Our 3. 3 minivan pulled it ok, but at around 2,000 lbs, it wasn't too great of a ride. A long tow would have been tiring with the minivan. The one year we pulled it with the Cummins was great - couldn't even feel it back there (or see it!).

That brings up another point. The newer pop-ups seem to be getting heavier - almost need an SUV at minimum to pull most of them now - unless you don't care about your transmission. Course, there are still smaller, lighter ones out there.
Our years with the pop-up were great. And the TT is really great now, too. It's just a natural progression, I guess. But no more upgrades for several years for us! I mean it!
