canon 650d experience
I upgraded from my T1i to a T4i a few weeks ago. I got a great deal from Canon direct on a refurbished camera with the 18-135 STM lens. I actually wanted the lens, and only bought the T4i when I realized that it would only cost $330 more than the lens alone. I sold my T1i for $260 on Amazon and it was a no-brainer. I'm very happy with my purchase so far. My thoughts:
For straight photography and image quality, there really is not much difference between the T4i and T1i. The biggest difference is that the T4i can set ISO speed during manual exposures when I use auto-ISO. On the T1i in manual mode and auto-ISO, the ISO would be set to 400.
For movies and live view – the T4i is pretty decent. It certainly is light-years ahead of the T1i.
I'll admit – I almost disabled touch screen thinking I wouldn't want to use it. But it really is well implemented, very seamless.
The focus performance should be a bit better for sports than the T1i because all points are cross points. I look forward to trying it out when my daughter goes back on the field in the fall.
Auto white balance seems to be improved.
The build in HDR and night photos features are nice additions. They would not be missed if they weren't there, but they seem like good additions.
The lens is great. Fast focus, very quiet, very sharp and I enjoy having a long focal length so this can be my every-day lens.
I was day dreaming of getting a 70D, but after having my T4i I think I'll only change if the upgrade is substantial. Movie/live view focus has to be quite a bit better AND image quality at high ISO has to be better. Improvements in handling won't be worth spending the money for me, I'd rather save my money. Well, perhaps until there is a good deal on a refurbished 70D.
In response to others: if you haven't already - absolutely spend $120 on a 50mm f/1.8 lens. Or perhaps get the 40mm pancake. You will be amazed at how much better photos are in low light with it. If you want, spend more on other low aperture lenses instead – but definitely get one. I waited years with my T1i before getting one. My first thoughts when using the lens were – this is what my DSLR is supposed to be like in low light!