I usually lurk but just had to chime in on this thread.
We started with a small pup, just 16 feet long when totally set up. A gas range was the only amenity. Pump sink and no toilet or shower whatsoever. No furnace, no refrigerator (just a small icebox) and no A/C.
However since it was small my Toyota Tacoma pulled it with no problem.
We now have a 23-foot TT and definitely enjoy the features. However I also had to upgrade the TV to a 3/4 ton truck and everything people have written about gas mileage is the truth. Plus I'm still trying to get used to pulling something that large behind me.
As others also noted, the increased storage is great and being able to get inside while "on the road" is a plus.
Yet there are pups that are larger and have plenty of features so who knows what our camping future holds?
One more point, when camping in bear country having a hard-sided rig is always better. (I hated having to put nearly everything in my truck's cab overnight when using the pup at Yellowstone!)