HMB is another one of those supplements that looks great on paper but the real world results didn't back it up. I tried HMB when it first came out and I honestly noticed nothing what so ever.
If you want to try it, it won't hurt you or anything like that but I doubt you will notice much.
If you want something tried and true to enhance recovery post workout - get a good quality whey protein powder.
All protein powders are not created equal. You really need to be a smart consumer in today's market and do your research. Look at the ingredient list and supplements fact panel on every supplement before buying it.
For a whey protein - you want to see nothing but that in the ingredients list. Whey protein isolate, natural flavours, a natural calorie free sweetener like stevia and then maybe some salt, soy lechitin and cocoa powder. There are a lot of good products on the market. I personally use isolation from n2bm.com. A good whey isolate should be pretty much fat and carb free. Isolation has 26g protein, 1g carb, 0g fat per 30g scoop.