I'm using a 3GS and am reasonably happy with it. Plus, you can get a used one fully unlocked for about $75-$80. Caveats are that there are several apps that I can't use and I'm maxed out on IOS 6. Most of the apps I can't use are games, so no deal-breakers so far. It's a little sluggish at times, but not terrible. Still faster than some of the Android phones I've used. It works fine for phone, casual internet browsing, most apps and music and the occasional video. The camera sucks so bad as to be almost useless except in perfect natural light (no flash). On the plus side, I don't bother having a bulky case because at that price, it's basically disposable if I manage to destroy it.

Take that review with a giant grain of salt though. Perhaps my satisfaction is somewhat linked to falling off the edge of the tech world and living in the jungle for almost four years.