Here are the negatives/bugs for me although overall I've been fine with the phone, some are a bit nit picky.
The signal for me has been slightly poorer than what it was for my DX. Wifi has been weak and will often freeze up (i.e, not drop when out of range or just not work).
My biggest problem however is that occasionally it just won't wake up. I press the power button and the screen stays blank then the lock screen shows briefly then it goes dark again. I need to do a battery pull to get it to work again.
I've also noticed very slow video load times from Instant Upload, these were the videos that are Google+. A 15 second video might take 30 seconds to load and will lag during the video. Meanwhile, watching a trailer on Flixter, for instance, take no time to load and don't lag at all. Also, the little video pop up feature is not available on all video playing. I think its just one the main video player. Still playing around with it.
I've tried the "Best Shot" feature on the camera which snaps eight pictures quickly and lets you pick from the best one. It seemed to work fine expect that all eight are then "instantly uploaded" to google plus. So while there aren't eight pictures saved on my phone, eight pictures still show up in the gallery, unless I go through and delete them. Very annoying. Its probably not a feature I'll use.
Battery life is ok. Part of that may be me still testing out different features and settings. For instance, the drive into work this morning burned 10% of my battery life because the uconnect feature in my car was accessing the map app on the phone. I think playing around with the features will reduce or eliminate some of my battery issues.
Some of the motion functions, like swipe to capture, are tricky to use.
I haven't used much S-Voice but my few times trying to use it didn't prove successful. I tried texting someone - couldn't pick the right name and then could choose verbally between the options given. I tried scheduling something - it kept trying to create a task instead. I asked a question - it did answer it. Overall was underwhelmed but I don't think that highly of any of these voice functions.
Very nitpicky: Don't like the stock wallpapers or ringtones. Notification sounds are excellent.
I was hoping that this phone would be better than the Nexus. So I don't know if I will leave my Razr for the S3. I was really looking forward to this great phone.