Well, I've had my LCD-X now for some months (coming up on half a year I think) and I do like some things about it as is obvious by me still having it, but it is far from perfect and I do catch myself considering selling it... But anyway, the impressions of it are generally that the tonality is brilliant, but I would often like a fuller sound, more bottom on it, though it is not as lacking as the LCD-3 in this regard. Likely this is more up to its increased impact than tonality. The biggest bone I have to pick with it is probably a lack of resolution and that it does seem to require a fairly loud volume level for the drivers to perform their best.
The volume level was too high for one of my friends and below this level it gets too dark and closed sounding. Mind you my reference when it comes to resolution is the HD800. But honestly, considering the LCD-X costs twice as much as the HD800 here, I think it is a "fair" comparison... To be honest, on all technical levels the LCD-X is greatly inferior to the HD800, but its sound signature is more to my taste a lot of the time.
Now I have the HD800 for really detailed acoustic music and progressive metal/death metal, the Fostex TH600 for the heavy rumble of electronic/ambient, and the LCD X for things in between like Jazz-Metal, Djent etc. But if Audeze and Sennheiser or Beyerdynamic even, worked together to make a headphone it might in my eyes be the perfect headphone!
My conclusion is to be honest that at new price, to my eyes, the LCD-X from a "subjective" or "scientific" standpoint is abysmal value compared to things like HD800, HE-6 or T1, but from a more subjective view it is a taste of something better that just isnt quite there, but the best we have got at the moment with that signature.

Oh, and I'm an absolute sucker for the build quality and heft of it, though I must admit it quite uncomfortable over time compared to my other two cans, though definitely not unwearable if you shift it a bit every once in a while...