I am using a Droid Pro, rooted with the CM7 ROM. I have had zero issues so far. I am a big fan of the candy bar with a physical keyboard. This phone has been discontinued so I am unsure if any future upgrades will be available.
There is a ICS rom out but the camera does not work at this time.
I bought one these used a few weeks back for a trip outside the US and I haven't switched back to my Samsung Fascinate. The stock OS has been really stable and the hardware is solid. It's a downgrade for me on the screen and camera, but I love having a keyboard again and it has been nothing but solid so far.