While one can complain about maras and PT'es I'd say that the biggest problem right now are the ops healers, they are in comparison to the dps burst classes way more OP. It's silly. As a level 11 sorc I had one healing me through a battle against two maras of respectable level. Don't get me started on a ball carrier with a dedicated ops healer.
I disagree that the sub-50 brackets aren't fun (the 50 brackets suck unless you hook up with some guildies or skilled guys on the fleet), but this I would totally agree with. Even when I was in recruit on my op healer, fighting against war heros, I was tripling the best enemy dps with my healing and dropping, at most, twice per warzone (usually zero times). THAT's overpowered. Any damager or tank I've played does die at least occasionally unless the enemy pug's getting steamrolled.