This is a very comfortable, lightweight, well ventilated helmet. The medium size just fits my 59.5cm head with only two small clicks of the rear ratchet needed from wide open to snug it down. It does not move around on my head when I go over bumps on my bike, sweat doesn't get in my eyes, and nothing digs into parts of my face as with some (much pricier) helmets.
Two gripes though. Firstly, the finish of the helmet is a bit slipshod, with parts of the polystyrene lining showing on the surface of the helmet where they shouldn't be visible.
Secondly, and more seriously, the detachable front cushioning pad is already coming to pieces after less than a month's use, and the tiny velcro pads inside the helmet that this pad attaches to are working loose. Apparently the outer layer of the cushioning pad is only held to the main body of the pad with some kind of adhesive and, guess what, this adhesive is water- and/or heat-soluble. This is not just not sensible, it is unforgiveable. All in all it strongly suggests that this helmet is made down to a price rather than up to a minimum standard. This is a pity because Bell (or rather the Chinese factory that makes the helmets) have spoiled an otherwise excellent helmet by neglecting a small but significant detail.