After watching WWDC's keynote I couldn't wait to get my hands on iOS 7. I was able to hold off for just under 2 weeks before I broke down and renewed my iOS developer license. I had been planning on playing with some HTML5/CSS3/JS -> iPhone platforms again which is how I justified it to myself. I downloaded the beta and restored my phone and here is what I found.
This is probably obvious to most iOS devs and probably the majority of people but even though I have installed betas in the past I never remember them completely wiping all my apps forcing me to re-download them all. It wasn't particularly hard to go to the purchased section in the App Store and re-download my apps and I took this opportunity to be a little picker about which apps I installed. At this point I had found a few little bugs here and there, mostly graphical glitches or the app freezing up.
Fast-forward a few days and overall I was happy with the new OS but on my iPhone 4S it was definitely sluggish and sometime completely unresponsive. I have a friend who installed the beta on an iPhone 4 and I can't imagine how bad that must be. Sometimes I will try to click on something and it just won't respond. Sometimes I even have to do a reset (hold home + power button till it reboots) to get the phone back into working condition. This was infuriating when it happened and it would happen when unlocking the phone, in the app switcher, and sometimes after waking the phone the running app would be unresponsive. The worst was getting stuck between the lock and homescreen (during unlock) because the "depth perception" would still work but tapping the screen/pushing the home/power button has no effect so you could tilt the phone ever which-way to see the cool depth effect but you couldn't do anything else.
I upgraded to beta 2 the day it came out and since I only had beta 1 for about 2 days before beta 2 I can't really speak to the changes between the versions. Unfortunately the Audible app does not work on iOS 7 yet (it crashes while trying to refresh your library) which means I have been carrying my iPad Mini around so I can listen to my book. There are multiple apps (PvZ being another one which has left me searching for another game to play) that don't work on iOS 7 yet which is to be expected at this stage. I'm sure 90% of the apps I use will work just fine when iOS 7 is released.
Overall I am very pleased with the OS. When it works it is amazing but when it doesn't I just want to throw it out a window. It transitions from being an extension of you into a pretty paperweight in record time but as I said above, I expect all of this addressed before the release. Even if it's not I plan on buying the iPhone 5S (Or whatever they decide to call it) the day it releases because my contract is up so I shouldn't have to deal with any of the performance issues I am seeing on my 4S. I look forward to the future betas and the final release, regardless of what others are saying about iOS 7 I think it is a step in the right direction.