I recently bought a Galaxy Tab 10.1. I mainly got it for reading and annotating PDFs and other electronic texts. For the same reason I once bought the first version iPad but quickly (after 1 week) sold it again since it was too much of Apple lock-in.
So far the Tab 10.1 looks pretty cool. It is light, has a nice screen, and the speakers are decent. It looks like one can more or less install any Android application from the Market. There are some exceptions such as Skype, Skype doesn't want to be installed on the Tab.
Browsing the web on the Tab 10.1 is quite fun. Like with the other Android devices Flash also works on the Tab.
All in all I think it was worth buying it, but lets see how long it takes until it will become a paperweight.