Although I think it'll take time for me to remember it's there, I'll be definitely making use of this handy feature. Especially when I can't be bothered to reply to a topic on a school morning.
Also, I just hate "Like" features on forums in general, or just about anywhere. There are problems I'd rather not have that the "Like" feature brings.
It's not really a rep system since users don't really gain anything or any rank other than advice or constructive criticism on their posts. For me personally, I haven't experienced or seen any major issues -- even little issues for that matter -- that have arised from 'like'/like-like features.