I play a 50 Marauder, and, while they dont "Suck" they are really not up to par with some other classes. They bring zero utility, they have 1 stun that breaks on damage and the other CC is channeled, they get kited and knocked back all the time. They can dish out good damage, but they need ALOT of gear to be up to par to a mediocre BH, for example. Marauder is probably the hardest class to master and the most frustrating one, but its not terrible.
If you didint break at least Duelist in WoW, you will suck at Marauder and get 1v1'd against any 1 who is good.
Good thing is, most people aren't so you can still have some fun.