This helmet is so cute! All of the Bern helmets are so much better looking than other bike helmets, this is easily the most attractive helmet I've ever owned. (I figured I would be more likely to wear it if I didn't feel like a dork in it.) I love the little visor. It's stylistically nice and I suspect will also be helpful in keeping the sun/rain off my face.
The sizing seems to be accurate. I have a pretty big head (hats never seem to fit me!) so the L did well for me. The helmet is a little heavier than I was expecting but not to the point that it's uncomfortable
I also really like the liner system that Bern has. It's nice to be able to swap out the lining from season to season. Though, to be warned, this product comes with ONLY the standard winter lining so if you plan to use it during warmer weather you should probably also buy a summer liner (helmet with no lining is really uncomfortable, and probably unsafe). I would also check out the Bern website and see if there is a different winter liner you might like better (they have 4 or so varieties). The liner itself seems to be really high quality, nice and thick with furry fabric on the part that touches your face and a mesh material over the top of your head for ventilation.
I got the white one which is billed as "Gloss White" but is actually matte. I didn't mind too much but it does seem to be more prone to getting dirty than I had hoped. I think a darker color or a gloss finish would be a better choice.
Overall I would definitely recommend this helmet. It's cute and comfortable and exceeds the recommended safety requirements (for biking at least). I don't think you can do too much better!