Just do what I did; go to a nearby electronics store and actually hold the Note 2 and S3 and feel them yourself. Since S4 is almost the same dimensions as the S3, it's still a pretty close match. See if the Note 2 is too big or just right, some stores might also provide a stylus so you can see how that works, as well.
As for myself, I think the Note 2 is just a tad too big for my taste, and doesn't really suit me. On the other hand, the S3 was small and efficient, so I'll definitely be getting the S4 when it comes out sometime in the next two weeks.
Oh, and @MikeLip: phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, phablet, tablone, tablone, tablone, tablone, tablone.