Just played with a 4 at a store. I own the 3.
When I got the iPhone 5, the speed difference between it and my 4S was like night and day. Comparatively, the speed difference between the iPad 3 and 4 is late afternoon and dusk.
They're almost identical in performance increase...the 4s to the 5, the iPad 3 to the 4. The new A6x C/GPU in direct comparison to the A5x. A6x clock speed is increased in the iPad, vs. the A6 in the iPhone 5. You should notice the SAME speed increase on the tabs as you did the phones if you're using them in the same way...we certainly have. From launching app speed to browser performance, editing photo/video and associated exportation of those files, absolutely no lag switching between apps (we own a pair of iPad 3s, and now 3 iPad 4s...we use hem extensively in the field).
That said, developers have only been programming to date the existing iPads. The 2/3 are essentially identical speed wise, in some cases--the '2' is actually quicker without all the pixels. I'm very happy with the perceived performance increase in the 4--and I don't totally disagree this is what the '3' should've been.
the sad part, the screen issues are still the same, no improvement there whatsoever.
??? What? Where is your evidence to back this BS up? All 3 of my screens are immaculate! Perfect in every way...of the half dozen reviews I've read, not a single mention of sceen issues...hell, there doesn't seem to be any extensive threads here OR @ apple.com discussing screen issues. Not sure where you came up with this, but I'd love you to direct me to any links or forums discussing screen issues...not the fact that you've returned a half dozen of them, but real people with REAL screen challenges. This is a non-issue...and IMHO, most folk just needed to get use to an accurate IPS panel last time around...in comparison to most monitors folks are used to using @ home for < $200...the panel in the 3 iPad 4s we've got are incredible!!!