Applications take a lot longer to launch, tapping on the keyboard lags sometimes, and Safari seems to crash a lot more often. It is certainly obvious that the 1.1.4 firmware is faster and a lot more stable. I am not saying that I keep facing those issues on a daily basis (although it’s true for some) but the difference between both firmwares is hard to not notice immediately.
Apple should have waited another month or so to fix all the bugs that most iPhone 3G owners are now experiencing before rushing it out prematurely to stores. I am certainly not the only iPhone user running 2.0.1 who is experiencing these issues. A quick search on Google will prove there are thousands more with similar and possibly more problems with the 2.0 firmware in general.