It arrived a couple of days ago but I've been busy cleaning up storm debris.
My first impression was 'WOW', this thing is as sharp as a tack. The monitor comes pre-calibrated and my only adjustment so far has been to back off the retina destroying factory brightness pre-set.
I've got it running side by side with my old S2209W and I was very surprised at how close the colours were. As the new monitor has been pre-calibrated at the factory it was a pleasant surprise that I'd got the colour set-up of the old monitor so close.
There is really no comparison between the two monitors as the new one's IPS screen and 2560x1440 resolution v the 1920x1080 res of the old one gives a far superior viewing experience. The blacks are blacker and the whites are whiter and no amount of fiddling with the old monitor can get it anywhere near close, although to be fair, it's about five years old and probably a bit tired.
All in all, a big from me for the U2515H.