As said before, it has slowed down my device significantly. Also, not sure if this has been posted, but if you have two albums that have the same name, but are by different artists, the album art and year will apply to both of them. If you don't understand, look:
I have two albums: one is Britney Spears'
Blackout, and the other is a single by Daddy's Groove & Cyrogenix, also called
Blackout. However, when I click on Britney Spears under artists I see this:
http://imgur.com/h984HqH.jpg
Similarly, when I tap the artist Daddy's Groove & Cyrogenix, I see the tracklist for the Britney album, and no track from that single... But other songs from that artist still appear.
http://imgur.com/qyQyI4o.jpg
This is probably the one I've noticed the most since I listen to music a lot on my phone. That along with the ones which have been stated before, like short battery life, slow animations, unresponsive touchscreen, etc. You'd think Apple would catch on to all these bugs before releasing it to the public? Guess we'll have to wait for iOS 8.1; hope it's not long until then.