g1 is a neat phone.. it does eat batteries for breakfast (brunch, lunch and dinner too).. it works perfectly with all your google accounts, i must say a very pleasant experience coming from a m$ windows mobile platform..
iphone works just as great, also not a long-lasting phone if you use wifi and 3g very often..
if you tweak your g1 to not use gps/wifi/3g/data services in the background all the time, people say they can get 2 or more days from their battery if they only use it as a phone
there are larger batteries available for the g1, they come with a modified back cover and boast 2400mah or more instead of the standard 1250/1400mah..
some things that still do not work on the g1 (dont know if they work out-of-the-box on the iphone though) are
- obex transfer to and from phone
- copy/paste from webpages
- appstore: no working turn-by-turn navigation app available (yet)
just my $0.02