Samsung Galaxy Tab is one of the first iPad Competitor that I think they might have a equal and fair fight. I haven’t have hands-on on Galaxy Tab, but from the Ad that Samsung just launched, it seems to be very impressive!
Samsung Galaxy Tab is 7inch, runs on Android 2.2 with Samsung TouchWiz. According to the Ad, it will run 7 hours non-stop, although it did not say if it is on 3G or Wifi. iPad runs 10hours on wifi, so battery life might not be as good as iPad. But there are alot of advantage, Android is open. You will have more controls over the Galaxy Tab than iPad, thus expansion slots and more.
Check out the ad of Samsung Galaxy Tab: