Pros: Comfortable, good bass.
Cons: Get a little warm on the ears after a couple of hours.
I'm new to this so take everything with a grain of salt, but I play guitar, and piano so I have a pretty good ear even though I don't know what I'm talking about I know what I like, and I like these alot. This was my first real set of good headphones. I had some $30 AKG plastic things that I thought were great, and some Sennheiser CX380 IEM's before, and was happy with both. Compared to all my friends and there Skullcandys they were awesome. Then I got these, and I was blown away. The cliche of hearing new things in all my music, and being like listening to all my music for the first time again applied.
Like I said I'm new to this whole thing, but long story short I bought these about four months ago, and since have gotten deeper into it. I now also have ME Electronics M9, Vsonic GR-04, Shure SE-215, Fiio E06, and last week got Beyerdynamics DT-880 250 Pro, Fiio E17/E09K.
Overall they are a good set of headphones, and a great value. If you are just starting with the whole audiophile thing they will do you wonders, but can quickly lead to a wallet draining aresnal.
My only complaint is that since they are closed back, and leatherish ear cups they don't breath, and my ears gets a bit sweaty after a couple of hours. But it is possible that is just a closed back thing. My new Beyers are ridiculously comfy for hours on end, but at this point that is all I have to compare.
In response to
"It looks like you appreciate the comfort level your new Beyerdynamic DT-880's have over these. What are your thoughts about the sound quality comparison between the ATH-M50S and your new DT-880's?"
To answer the question in my not know what I'm talking about version of the vernacular. They Beyers sound better. Not as much bass, so for some stuff I am fiddling with EQ's, but haven't found anything that amazes me yet, and they are bad enough to demand some EQ. So I'm still up in the air for that. Have some Nickel Creek going right now, and it is just about perfect for that. The sound stage is definitely better, although the M50's being my first real headphones I thought they were pretty good. From what I have gathered, that is a consequence of the open back (the DT-880s are semi open back whatever that means).
I have only had them for literally two days so far so I haven't had much chance to really pay attention to the little details yet so I can't say any more than they sound better in almost every way, aside from the aforementioned bass.
But the caveat to that is that the 250 pros won't run very well on the same setup as the M50's. I have the gain turned down, and lo bypass on the E17, and the gain turned off on my E09K, and that setup runs about half volume on the E09K for normal level, and cranked is just on the loud side of the loudest I would ever want to listen to it. But I tried it with my phone setup (Droid X2, and Fiio E6, and I had to crank everything to get it to just above normal listening volume, versus the M50's which would blow my ears out with this. So the 880's (at least the 250 version) need more oomph to get them going. So you may have to change you setup if you switch between headphones. From my collection I can say the they all run on the same basic setup without issues aside from the Beyers. Due to that I can't say what is strictly the Beyers, and what is the new setup. Since they are nicer they were intended specifically for my home setup at my desk, and the M50's are my around the house, and at school over ears. But I can backwards compare them with the M50's on my new setup and they definitely don't have the bass, but everything else is better, which if need be can be doctored with an EQ a bit.
Sorry for being a bit rambly.