my biggest issue with google is the unpredictability. i think their new phone Nexus One is slick, and the OS is shaping up really nice as well. however....the problem is that some phones can upgrade, some can not. and they seem to be releasing new updates/phones very frequently, making your model outdated much quicker. also...they are treading into dangerous territory by competing with their partners...but we will see how it pans out. overall i just see them as more chaotic and unpredictable.
not a fan of nokia myself, but i know others like it much.
iphone 3Gs is super quick, and sleek, and has the app store to back it. to me thats still the winner, but i would keep an eye on google in coming year. they may be able to really pick up a storm.