Fed up of my GS3 (i9300). Fed up of Samsung Wizz all over Android. I started with a HTC Magic then a Nexus One, but then I switched to a GSII. The GSII wasn't too Samsung'd back in the days of Gingerbread, but Samsung have gotten worse with the "value add" since then. Mostly junk though. The Galaxy Nexus didn't give enough reason to go back to Nexus so ended up with a GS3. The GS3 has a pretty decent camera, but the general performance isn't great now. Chrome is very slow to load at times. Things are much quicker on the Nexus 4 (wife has one).
So long as the Nexus 5 has a better camera than the GS3 I'm on board for sure. I have got used to being able to swap my battery for a spare, but I think I'm just going to have get over that as more and more phones are doing non-replaceable batteries now. As for the SD card thing, I don't load videos or big games onto my phone so should be able to manage with the 16GB(ish) space.