My first concern is which Rondo we will get - Dallas or Boston. If it's the former, we're screwed. If it's the latter, we have an all star calibre PG.
My next concern is after seeing what went on in Dallas I didn't want him. He was apparently disruptive and not a good teammate. If true, that makes this a risky move. But hopefully that doesn't happen here and he becomes a leader on this team and returns to form.
The final concern is that he does really well with us and walks in free agency. That would be just our luck...
That said, this might turn out to be a very good signing if he returns to form and ultimately commits to this team long term. Won't please Collison though, maybe he'll end up being traded?