Weak river play?

[Entity]

Edit: Converter is screwy. I'm BB, not MP, and the only person at the table I've played with before is on my left, and is not involved in the pot.

Party Poker 1/2 Hold'em (6 max, 6 handed) converter (http://www.selachian.com/tools/bisonconverter/hhconverter.cgi)

Preflop: Hero is MP with A/images/graemlins/diamond.gif, A/images/graemlins/club.gif. Hero posts a blind of $1.
CO folds, Button folds, SB completes, BB calls, UTG calls, <font color="#CC3333">Hero (poster) raises</font>, SB calls, BB calls, <font color="#CC3333">UTG 3-bets</font>, <font color="#CC3333">Hero caps</font>, SB calls, BB calls, UTG calls.

Flop: (16 SB) J/images/graemlins/spade.gif, 5/images/graemlins/club.gif, 6/images/graemlins/diamond.gif <font color="#0000FF">(4 players)</font>
UTG checks, <font color="#CC3333">Hero bets</font>, SB folds, BB calls, UTG calls.

Turn: (9.50 BB) 9/images/graemlins/heart.gif <font color="#0000FF">(3 players)</font>
UTG checks, <font color="#CC3333">Hero bets</font>, BB calls, UTG calls.

River: (12.50 BB) 5/images/graemlins/diamond.gif <font color="#0000FF">(3 players)</font>
<font color="#CC3333">UTG bets</font>, Hero calls, <font color="#CC3333">BB raises</font>, UTG folds, Hero calls.

Final Pot: 17.50 BB

[Gravy (Gravy Smoothie)]

Looks OK, I hate having to call the river raise but at the very least it's worth it for the information.

[Entity]

Does anyone like going for overcalls here on a sudden river bet?