Just tried out the GM on an ipad 2. (First time using ios 7 also)
Runs faster than I thought. Haven't had any keyboard lag. Video controls are very ugly. Are they missing a blur effect?
Some parts look good without blur such as the keyboard. Popovers look poor without the effect.
UI elements in all the Apple apps and home-screen icons look ugly without retina IMO. The multitasking is a downgrade for me - allowing animations to be interrupted would fix it for me. It also should snap to the next app instead of scrolling past it but that's just me not being used to it I suppose.
Text selecting and cursor navigation is more responsive than ios 6 on this ipad which nearly makes it a must-upgrade by default.

The resulting copy/paste pop up doesn't look too pretty though.
If it uses more ram then I haven't noticed so far. Safari is very smooth. Pages don't reload too often - seems the same as ios 6 with regards to page refreshing.
It just feels unfinished for a GM on the ipad 2. The performance is there thankfully but the UI needs some polish. I just can't unsee the aliasing around the app icons on the home-screen for example. Pinching to the home screen exhibits a weird animation glitch that is always noticeable.
If Apple bug fix the 7.0 like they did previous ios versions then I definitely will upgrade. Just needs more fine tuning for me currently. At least it still feels fast though. That was main worry when running it on the ipad 2.