I've always found it very hard to find good fitting suits off the rack that I could get altered. They've always been very big, and tent like around my torso, and baggy in the pant legs. I have fairly broad shoulders, yet I'm very lean in the thoracic region. I'm 5'8 1/2 exactly and I weigh 130-140 on any given day. I'd personally like to gain some weight, and I do... but it never stays on.
H&M's quality is not the best, the stitching and fabric isn't as good as some of the $500 'tent like' suits that I own. Their suits seem to be perfectly fitted for slim, and slender guys. The cut is amazing if you're around my size. I purchased a 34R, and 30R pants. I'm going to post a picture to let some see how the suits fit, and also ask if it looks proportionate and fitted right to me. The picture was in a dirty mirror, and It's not full-length. The pants still need to break right, and they will be altered soon. They fit amazingly snug though; I love the look. I think the jackets sleeves might be a bit too long, or perhaps the slim fit shirt I boughts sleeves weren't long enough. Let me know, I was going for a short jacket, and narrow lapel look.
I may actually get suits tailored in better fabrics accoring to how these H&M one's are cut... at least when I finish college this year. I hope someone stumbles across this who may have had the same problem as I did.