I picked one up about a week or so ago, I'm really like it so far. As Sazar said, the Android 3.0 OS still needs some fine tuning. Also app developers need to update their apps to support the larger form factor (or stop crashes) but over overall I'm happy.
I've not rooted mine yet, simply because there doesn't seem to be much reason to do so right now. I'm keeping an eye on the dev threads over at XDA though. As soon as the juicy bits start showing up for rooted Xoom's I'll likely jump right on it. I've not seen any actual custom Xoom FW yet, just custom kernels for OC, etc.