It is one of the best and cheap site if you have something to outsource. I've used pinterest many times. Once I've bought a gig for increasing the like on my YouTube Video. Thus I got 1000+ likes and my total youtube viewers of that video increased to 6000 within a month.
Later I've bought another gig to get more like+retweet+SU+digg (in a single gig). But it was a crash. This does not increase my traffic. A-listed bloggers like Daniel Scocco of DailyBlogTips.com also use pinterest to get more likes. So it is worth trying.
Do they really get engaged, read the post??
No, if you want to get more likes, say 1000, they simply like it and not engaged on it. It simply increase the number of followers. It also help to get more traffic due to viral effects and sometime it may be a real crash. Anyway, it is all about $5 and it is definitely worth a try.