It’s not bad for leveling but the other specs are better. If you want to go prot, ignore the hyperbole on these forums but keep in mind that you will mostly be solo’ing as an untalented arms warrior (except for tactical mastery which you should get early on). Once you get shield slam, it’s pretty smooth. Either way, it’s easy as long as you keep your gear current (which you should since there is no point in being prot unless you are running dungeons).
I should note that this is for PvE. For PvP, you’re pretty much a target dummy.