No, not really.
Upgrade time for our household was the first of the year, and my wife volunteered to take my iPhone 4s I bought used out of contract and let me get a iPhone 5. (Don't hate or judge, she gets to drive the new car.) We both decided that we'd keep an upgrade in our pockets just in case. Since she was already carrying around an 8gb 3gs with a broken screen for a couple of months, waiting was not an option.
Coming from a 4s, the 5 is nice. Like the extra screen space for occasionally looking at ebooks, etc. I marvel at how comparatively light and thin it is. But the only time I can really tell a noticeable difference between the two so far is using the camera to deposit checks with my mobile banking app.
If they released a new iPhone tomorrow, I'd be okay with it. We all know a new model will eventually be released anyway, and I was satisfied with my 4s. I wouldn't even contemplate a new phone out of contract unless it had an absolutely OMFG feature or upgrade. A marginally faster model with a bigger screen alone won't cut it.
Same thing goes for our 2nd and 3rd gen iPads. Call it marginal contentment or upgrade fatigue, either way.