As a level 37 paladin, I've found blacksmithing fairly useful - most of the armor I'm wearing now, I've made. Of course, I haven't done very well on drops and I refuse on principle to buy all the good stuff from the auction house (although I don't have that bias against vendors!), and I don't have a guild to supply me, so that may make a difference. I understand there are some very useful toys that an engineer can make and use that you can't get anywhere else which can prove extremely useful to a paladin, and if I had it all to do over, I'd probably go that route, but so far, smithing's been very very good to me.