I ordered my Xoom off Amazon a couple of days ago. I probably shouldve waited for the Galaxy 10.1 but everyone keeps saying Samsung is epic slow with their updates...If I don't like the Xoom hopefully I can return it back to Amazon for a full refund and get the Tab. I dunno yet. Also I spent a lot of money on accessories for the Xoom. But from what I've researched and the little time I had to play with the Xoom, I dont think I'll be disappointed.
To be fair, Samsung is actually pretty good with updates. It was the carriers in the US that delayed the software. Europe and Asia got their updates months ago and the Galaxy S and original Tab are still being supported.
Engadget have reviewed the 10.1 Limited edition from Google I/O and are saying it's as good as the iPad and the best Honeycomb tablet yet:
Samsung Galaxy Tab 10.1 Limited Edition review -- Engadget
Will definitely be trading in my Xoom for one of these.