The one thing I hate about any type of iPod/iPhone is the lack of micro SD card slot. I can get two 32GB cards for $40 each (as of today on Amazon; when did they get so cheap? I swear a couple of months ago they were almost twice that.) giving me 64GB of extra space for roughly 2/5th of the price to jump from the 16 to 64. Of course, the downside is that I'll probably eventually lose at least one of the cards.
I'm not necessarily underwhelmed by the 4S, since there definitely is a speed bump, memory increase (I think?) and better camera (anybody truly complaining about the lack of change needs to look at various Android phones. I'm pretty sure, at least on HTC's end, that the only differences with the last few phones they've released just have slightly better specs than what they released back in March and different housings. The Thunderbolt released back in March has somewhat similar specs to my HD2 released a year prior.) but I am really disappointed that they didn't increase the screen size. I'm used to 4 inch screens on phones, so the iPhone screen is a trifle too small for my liking for most of the things I do. Also, the housing the iP4 uses is probably my favorite to look at and touch, but I abhor wielding it. I can't seem to find a position where it feels comfortable in my hand. I could use a case, but it ruins the point of having a nice-feeling phone if I cover it up with silicone.
If the iPhone 5 has a quad core processor (hell, quad core isn't even that important to me since what's out now seems to be sufficient to my needs) and a 4 inch screen with a more hand-friendly housing, the same dock connector, and cheaper memory prices, I'll probably buy it if there aren't any intriguing Tegra 3 phones out by then. I want to see what Nokia has in store too. WP, as much as I hate to bring them up in an iPhone thread, seems promising if given time to mature.