I wouldn't say any of the skills are overpowered but there are some that completely aren't viable at all. It's like they gave us some decent skills and then a crap load of useless ones that hardly anyone will ever use because they came in the box broken.
Here's a few examples of skills that simply don't work.
Chakram - Same hatred as elemental arrow except it has one insanely huge flaw. It can miss enemies that are directly in front of it. Even if you line the shot up and try to stand a close enough distance, you severely lose damage every time it randomly misses.
Companion - You've got the ferret for MF and the bat for hatred, the rest do such little damage that they're completely pointless. It doesn't make sense to use this when it strikes maybe 5 times during a 40 second battle and only does perhaps the same damage as 1 hungering arrow/grenade/even chakram. Needs buff.
Spike Trap - AMAZING skill! I love this one to death because you can kite the enemy to their death! Fatal flaw: 30 Hatred per cast with absolutely NO way to reduce costs. Seriously? You can use this 4x and that's all she wrote. When you've only got 125 hatred and you have other things like impale/elemental arrow that you can use on single targets, why would you use spike trap? If it was 15 hatred or even 20 hatred, it would see a lot more use because the damage would be worth it. But 30? You'll run out way too fast.
Cluster Arrow - Another really cool looking skill that I'd like to use... more than 2 times. This skill costs 50 hatred and can be reduced to 40 through a passive. Yay 40, now I can use it 3x. Needs fixing.
I'd really like to see these skills fixed because they CAN be very good. It just doesn't make sense to create a class and use such a small resource pool then smack on an incredible cost for skills. The only way I could ever see cluster shot working is if you can manage to find minus cluster shot gear, use the rune, and have really strong hatred regeneration. I'm not sure if blizzard tweaked with this specifically in mind but the cost is way too much at base level.