Well, decided to keep my S3 and not swap it for the Note II. It dawned on me that I'm not really likely to use the stylus all that much, and as much as I love the split screen multitasking, not sure for me personally it's worth it for the size and more importantly, weight trade off. But if you're not as fussed about weight/size, nor shallow like me, you might much prefer it.
After comparing extensively with my S3 and the iPhone 5, it dawned on me that mobile tech is sort of at a point of near parity. A big hoo ha is made about otherwise small things, like pentile, whites, blacks and all the rest, but when it comes down to it there's little separating them. Ok, so the Note II's screen is a bit better than the S3's, but I don't think you'd really notice the difference unless you were really seeking it out or pixel peeping. I actually think many consumers will prefer the S3's, purely because it's a bit more punchy and has ever so slightly more obtuse shadow detailing. Even the whites thing is blown way out of proportion.
I also found that when comparing web pages etc, my eye sight is still good enough that I can make out the same tiny texts on both the S3 and Note II, so the extra screen size didn't magically make illegible text legible, no matter how small the text, it just made it a bit more comfortable to read, or allow me to view pages at a further distance from my face. End of the day, they're both still 720p.
Aside from that, the S3 is still marginally more snappy in certain things. Not with the UI thanks to JB, but certain apps. Even web browsing at times by a hairs fraction (with flash support, which imo still comes in handy), and my S3 is not even on the Jelly Bean update yet.
JB on the Note II with general UI use though, with transition, window and animator scale set to 0.5x in developer options, is among the smoothest and quickest OS I've used.
Also, the camera seems the same as the S3's, though I did a low light test with the iPhone 5, and honestly, I felt the S3 and Note II came out on top every time. I don't know if it was the scenario or what, but whilst the iPhone 5's shots were ever so slightly brighter, they were much noisier and less detailed than the Samsung counterparts, so I'm not sure what's up.
Anyway, thinking of filming an extensive comparison video between the S3, Note II and iPhone 5 on my DSLR, but figure I'll wait till the official UK S3 JB update is out. If I can be bothered lol.
EDIT: One thing to add, the Note II's loud speaker blows away the S3 and iPhone 5's. It's louder and bassier. In-fact, I was quite surprised at how well it did hip hop. If you use Navigation a lot, you may want to consider the Note II over anything else because that huge screen coupled with that very loud and clear (by mobile standards) loud speaker should be ideal.
