Pros: Cheap, good lows, extremely comfortable, sort of isolating, short wire, tiny plug
Cons: Headband and joints feel flimsy, veiled and uninvolving mids could use more definition
It's an unfair comparison, but I'll compare them to AKG K 272 HD, source being FiiO E7 USB DAC for both. (I equalize the AKG by +3dB through 20-80Hz)
The soft, pillow like earpads are a godsend. The leatherette feels comfortable, and doesn't cause sweating. The joints and headband aren't as assuring, and feel prone to breakage. Since they're a gift for my gf I won't break them just to try it out. Oh well, atleast they're very light and you just forget about them in five minutes. The short cord has a cute tiny 1/8" plug that won't get in the way with portable use.
First time playing Ayreon on them, which has plenty of beautiful female and male vocals, melodic instruments, reverb and all sorts of funky effects, I found the XB-500 mids lacking, and they just didn't seem to come from anywhere in particular, and there was this weird veil that took all the detail away. After the headphones had burnt in my ears in a week, the mids didn't bother and I wholeheartedly found the sound enjoyable, with a really entertaining lows and good highs. For 40€ the SQ is great, although bass at times felt a bit bloated and uncontrolled. With gaming the mid-range veil and smooth bass are a non-issue, and in gaming the soundstage doesn't run inside my head too much, so for gaming they're a really valid option, although they're certainly not horrible for music use either. Definitely not for the most critical listener, though.
When my ears had settled for these cans and I swapped to the 272 HD, my ears faced a complete blackness in mids and highs and the dimension was far greater than with the XB-500, like there'd be another world inside the headphones. The bass felt a bit clinical and fell short after getting used to more, so props for the XB-500 making things sound 'fun' and groovy. All in all I preferred the bloated bass while gaming and listening to some genres like dubstep and rap, but with dance, metal and electronic music the 272 HD feels much more at home due to the crystal clear detail all around (especially when the shortcomings of bass are equalized.)
I'll listen to them for a month before handing them to my gf and see if my opinion changes, but I think I'll look for Beyerdynamic offerings the next time I feel like I want something with bass. They're a lot more expensive though, so I've got to cut the XB-500 some slack and admit they're awesome for the price. I'll try out the XB-700 if their mids would be better. I'm not rushing to the store to get another pair of XB-500 for myself, I'm sure my gf will plain love them! Although the overall tone of this review is positive and I like them, there's just something I'm missing that I have in the AKGs, hence the sub four star rating. Still, great value.