Its pretty good. It does struggle with games a little & chunky CPU stuff, its camera sucks & LG windows software is a royal PIA but apart from that its a damned fine phone and a bargain for $180 or so.
I reckon the P500 is kind of shit. Mine "loses" its SD card all the time, meaning I got to open the back cover and wiggle it about. It has also taken to just sometimes turning off. And loads of apps (including facebook and gmail) crash on it.
I suggest you avoid that phone. Get one of the cheaper Galaxy phones. Samsung is awesome.
I had the real cheap IDEOS one. CRAP battery, and was on 2degrees which had no coverage at my work. Returned it and got the Samsung Galaxy cheap one instead and on Telecom prepay. Has everything you're looking for, battery life is still only average, but if you keep the screen brightness down it's not too bad. (at least twice as long as the IDEOS one!). Now I want a Galaxy S2....I'm just about $950 short for it.