tbh he's a great hero but there's 3 weaknesses he has from what i've seen
1) easily counterable / gankable with a well placed counterward. place the ward in a position where you can defend it if he tries to kill it
2) pub players tend to play overly aggressive on him. if he exposes himself from net and you have stuns when he's chasing 1 player, he's pretty screwed
3) late game, his pet dies so fast to physical DPS you can basically kill half of tremble's effectiveness very quickly