I'm running 6.0 and have nothing really all that bad to report. Everything's still beta so there are a few non-functional features. The GPS works, the camera does too but it behaves awfully strangely. I have no idea if the FM radio works as I've never had use for that feature. The only features that I really miss are bluetooth (which I'm sure is coming) and the spell checker (which I'm told is a matter of taking a few files from the standard GW620 software and transplanting them).
Apart from all that 2.2 is wonderful. I'm getting improved battery life 70% remaining after 25 hours off the charger. The phone also works a little more smoothly and the Froyo interface is a lot nicer to use than what LG originally gave you. The integrated task manager and the toggle widget alone make Froyo a must have for me - oh, can't forget the numeric battery meter. These three features have replaced every widget I ever used on 1.5 which I'm sure is a contributing factor to my improved battery life. The voice features are also surprisingly useful. So long as you can enunciate everything clearly it really does pick up and put down everything you're saying.
I feel I should also note that this was my first attempt at doing anything to my phone. Prior to the 2.2 update I hadn't even hooked my phone up to my computer. The installation instructions on OpenEtna are a little fuzzy for the first time user but, really, spend a little bit of time getting acquainted before you hook up your phone and you shouldn't have any worries.
PS. My average daily use includes Facebook, Gmail and several dozen texts.