Ride quality tends to be firm, to say the least. In the case of the SRT4, it actually wasn't nearly as bad as I'd feared. As a trade-off for performance, I think most would find it entirely worth it.
The Caliber's biggest problems are its boxy, upright shape and the fact that power goes through the front wheels alone.
All in all, though, the SRT4 is a puncher, not a dancer. Suspension upgrades or not, this is a miniature muscle car, made for off-the-line thrills, not twisty-turny fun.