I use the whole suite, but for a photographer, the difference (in phootshop) between cs4 and cs5 is pretty minimal - a couple of improvements to selections, thats about it
I not sure why you think this unless you have not updated it.
ACR has lens correction built in so now if you have a 10mm lens it can correct it with CA adjustment as well as you can find turn them to your camera and lens and save this info, in PS the content aware fill or healing is magical as well.
I think it is much better then CS4
Plus I keep finding new things about it You need to get over to Russell Browns web site to find out more.