Good move by both sides. I was wondering whether Daniels would refuse to return because of losing his job last year, but I think this is the best move for everyone.
The C's get at worst a quality NBA player who can eat up minutes behind Pierce and Allen, and at best, an absolute steal if he returns to form. And they also now have more flexibility to hold on to Sheed's contract until the trade deadline, when there may be more sellers, if they can't find a good deal before then.
And for Daniels, he gets a chance to showcase himself again on a contender. He just needs to stay healthy, and you know, play well.