I really dig these shirts, especially for what I paid off SAC. I'm not crazy about the strange collar/neck construction, I prefer a normal circular cut. However, that's about my only complaint! These shirts are pretty durable (for merino), they wick sweat very well, dry quickly and they don't smell (that bad). I don't own any icebreaker shirts so I can't compare, but my patagonia merino 4 smells a little better than these Stoic merinos after some sweaty days. If you're a little chunky in the midsection (fatty) don't buy, or size up. You have been warned so no bad reviews about how you thought they were tight, and that's the shirts fault... they have a very athletic fit. I think improvements would be: Arms a little bigger, normal collar. The second just being personal preference though. I'm very happy with the two shirts I have, they work great and were an exceptional value.
5'10/190# Size L fits me just right, read above though. Not for chunky drawers.