I bought these due to morbid curiosity; Skullcandy made a gaming headset? I figured I try them out because I was getting tired of my X12s, which had replaced my X11s. The SLYRs have now replaced my X12s.
One fact to know about these headphones are that they were mostly designed by Astro Gaming, as Skullcandy bought them. This changes everything
The sound quality is astounding and the way the headset is built is just perfect. But as you see in my cons list, they are uncomfortable for the first few hours; I believe it could be because your ears are fully encompassed in a smaller, rectangular hole vs the X12s larger round cups. Now after you wear them so that your ears are broken in, these become very comfortable. The cushions are soft and velvety and the headset is fairly lightweight .
 
Now the features of the SLYRs are what really made me love them; the cable doesn't stretch to the moon, I can see the volume control module due to the light surrounding it, and I can detach the headphones and plug them into anywhere with a 3.5mm jack; yes, the headset can become headphones and travel with you, which the X12s fail at. 
The sound quality from the SLYRs blow the X12s out of the water. I can hear so much more stuff and tiny details on the SLYRs than I could on the X12s. I also could hear that is more direction to sounds than on the SLYRs than what the X12s could provide Even though there are only three settings for bass on the control module (stock is the best), the SLYRs still provide some substantial boom without sacrificing the mids and highs. Now when it comes to adjusting volume, the X12s are definitely easier to work; the SLYRs control module has (instead of separate wheels for game, chat, and bass) a multi-directional square for game and chat, and a small switch on the side for the three levels of bass (thin, full, muddy). The idea itself was a neat idea, but the usage of it is enough to drive the wearer up the wall. If you push/hold the square up or down, that will control the main game volume, which by itself is perfectly fine, but as soon as you throw in in-game chat the whole module design shows it's flaw; to turn the chat volume up or down you push the square side to side, but if you turn the chat up you simultaneously turn the game volume down; chat volume up = game volume down, vise versa. it takes for-freaking-ever to get used to the volume control, and even after you do, it still sucks. That being said, it's still not enough to walk away from these headphones as a whole.
 
When it comes to music, you will not be disappointed. These are definitely the best headphones Skullcandy makes, but it's strangely ironic that they didn't design it. I'll do small comparison test with the SLYRs vs my Sennheiser HD 380s; the HD 380s are the best sounding over-ear headphones I own, period, but as far the SLYRs go, they are not anywhere near bad. The SLYRs can perform very well in the music department providing an excellent balance of mostly bass, mids, highs, and treble. After playing with the EQ in iTunes, I found myself on "classical" with these headphones. I then tried to see what they sounded like with the most bass possible, so I set the EQ to "loudness" and proceeded to have my ears drowned in some pretty great bass. It's so much bass on that setting that you can feel the headphones vibrate from the outside. The combination these headphones provide is great for any style of music. Is it the best ever? No, but it will leave anybody satisfied. And as far as I know, the SLYRs are the only gaming headset with a detachable wire, which makes the SLYRs a perfect combination; providing you with a great gaming experience and excellent music.
 
If you want to by a great gaming headset and simultaneously get a pair of some excellent over-ear headphones, the SLYRs are worth every penny

I'd just like to say the audio jack on these are of a very smart design; the cable goes into the jack at a 90 degree angle and doesn't shoot straight out. My last pair of earbuds died because of my hand accidentally smooshing the standard jack. I can already tell that these UE500s will last a very long time.
That said, they sound fantastic. I prefer these over my mothers UE600s because the 600s sound...flat? The 500s sound more rich than the 600s. The only thing the 600s are better at are fitting in your ear. But, the overall value you get from the 500s is, in my opinion, better in terms of sound and isolation.
If you get these brand new, they include a little box to carry them in and some comply-foam tips. However, if you have other buds that you like, you can just slide any on or off. 
You will not be disappointed if you get these. They can serve a variety of activities and have good noise isolating capabilities.
The link below is a total steal on these earbuds. I suggest you buy now.
http://www.amazon.com/Logitech-Ultimate-Ears-Noise-Isolating-Earphones/dp/B003YKG2XM

    I have been using my X12s for a little more than a year and they never cease to amaze me. It makes gameplay so much more enjoyable because of the enhanced sound and adjustable bass levels. When I'm playing games in Halo, I can always tell what direction my foes are approaching me from because the X12s allow you to hear pretty much everything. They are also comfortable, enough; the tops of your ears may get sore after a long sitting. In my opinion, the X11s (the model wich these replaced) were a bit more comfortable because they where a tad lighter. But the X12's sound quality is by far better. 
    The only legitimate problem I have with these may be in my own ears, but if you turn the volume al the way down, and then slowly increase it, the right side is always the first one to emit sound. This 'problem' is insignificant and possibly invalid because it may only be my left ear's fault.
    Aside from gaming, and if you have the right adapter, you can actually power these headphones with an i{Pod/Phone/Pad and listen to some tunes. The only issue with this setup is that the cable is almsot unbearably long and has an assortment of other connectors (use the green audio jack for MP3 players). If you don't have over-ear headphones, the X12s can suffice until you get a pair of "real" headphones.
    As for comparison with the other models of Turtle Beach Xbox 360 headphones, I cannot justify buying any other model of headphone; There are a few options and prestigious features such as wireless connection or Dolby, but to be frank I have not been super impressed with the higher models. If you do want Dolby surround sound, Turtle Beach had a processor add-on available for the X12s that will convert them into a 3D audio capable headset.
 
If you are looking for a great sounding gaming headset and don't want to put a hole in your wallet, look no further than the X12s.