I found the headphone a little tight at first, but if you bend the metal headband a bit and loosen things up, it helps with the comfort level and I liked the microfiber cover on the earcups. I wouldn't call these the most comfortable on-ear headphones I've tried, but with some breaking in, you should be able to wear them for longer listening sessions without a problem. Then again, each head is different, and some people may have an issue with their fit.
Overall, the the On-Ear seems well built and it's nicely weighted -- not too heavy and not too light. I didn't find it as sturdy as the V-Moda Crossfade M-80, which lists for the same price (around $229) but is being phased out for an as yet announced new model (again, the On-Ear doesn't fold up while the M-80 does, which is nice).
As for features, the headphones have a detachable cable and you get both a standard cable and one that has an Apple-friendly integrated remote and microphone for cell-phone calls (some of the remote features won't work with non-Apple mobile devices). Alas, like the bigger Momentums, these don't fold up or flat but they do come with a nice carrying case.
The Momentum On-Ear has a lively sound signature; you'll never feel like you're missing anything in the mix. Clarity is a big part of that, and then you notice the bass. It's powerful and outperforms the V-Moda on-ear Crossfade M-80's prodigious bass oomph. The On-Ear also sounds more open and less "canned" than the M-80. The headphone's sure-footed low bass performance will please listeners of EDM, rock, and hip hop.
So how exactly does it compare to its bigger, more expensive brother, the original Momentum, an audiophile favorite since it was introduced last year? Well, the larger Momentum shifts the tonal balance, it's a warmer and richer sounding headphone. It's just as detailed, but acoustic instruments and vocals have a more natural, full-bodied tone.