When healthy, Warrick and TJ share punt returns (that's how it's always been, and will remain). On kick-offs, TJ splits returns with Kenny Watson (even though they don't seem set on these two guys.
TJ is an extremely good receiver, better than Washington. He kinda has a mouth on him though. Marvin Lewis seems to like him as he kept him on the roster all last year even though he was injured (if he was on the IR which I don't think he was, it wasn't until later in the season). He cut some pretty good WR/Special teamers in Ron Dugans and Danny Farmer to keep TJ around.
I see TJ easily being the #3 receiver, and #2 when Warrick is hurt - which will be off and on all season, probably more often than most people think.