I've had him played against me once where it actually won the game, but the rest of the times it did nothing more than a 6/6 and a few times it actually won me the game by healing me twice in a row or sheeping the tinkmaster then itself.
Just faced a hunter in arena at 7-0, fucking annoying deck he had 3explosive, 2frost traps, savanah+hyenas+kodo charger, and then when I thought I finally had board control(at the expense of my health, I was playing rogue so had to weapon facetank some shit and all), he fucking turn 9 charge dino shit, didn't even know that card existed. Dropped me to 5 health, thank god I had enough cards on board to kill it and still retain my stormwind commander, and finished him before he could steady shot me to death. Finished with 1 hp, close game. Think it's first time I got to 8/0, I then played 3 more games just attacking into creatures I couldn't kill and passing turns. My rogue deck was pretty good, tons of creatures and most of the good ones, a few bigger guys for late(stormwind commander, core hound because the other 2 cards were shit and I figured why not and venture co merc cause I love this guy) and quite a bit of control. No backstab, only one draw(shiv), only one assassin blade/no perdition, no SI:7. Overall a shitty "rogue" deck, but a good neutral deck.