Hollweg is a gritty player. He's good in the locker-room and well liked by his mates. In fact, he's often called a "team guy". Hollweg plays hard and he's sound defensively. He's quick and he's aggressive. This combination makes him something of a human wrecking-ball on the ice. He'll fly from side to side hitting anything that has the puck (or not). Hollweg also makes your team tougher. He's happy to fight. He's not scared to stand up for his teammates. Oh, and as a bonus, some of his best days were playing on Dominic Moore's wing as a fourth-liner in NY.
That said, to call Holly's skills "limited" would be to misuse the word "skills". Hollweg can't really stickhandle. Or pass. Or think his way around the ice. OK, maybe from time to time he can do some of these things, but he'll flub his best chances and brain-cramp at the worst possible times. He takes untimely penalties. These will get old fast. Worst of all, you'll hate his propensity to board opponents. They could rename "Boarding" in his honor. It's painful to watch. It's what got him slashed by Chris Simon and it has drawn the ire of the league office from time to time as well. I doubt he'll be able to hide his tactic in the limelight of Toronto any more than he was able to in NY.
All in all, Hollweg is a role-player with limited talent. He works hard, but he’d be well served to eliminate his tendency to hit players from behind. You could probably do worse as a fourth-line player. I would have traded him for a 7th rounder. I think getting a 5th rounder in return for him is a steal (if a 5th rounder can be considered such).