Cant give you a hands on review, but my Dad has just bought one to replace his A100. He reckons it is well worth the upgrade and a considerable improvement. Pictures are sharper and seem more detailed, lcd screen is bigger, it has a colour histogram, higher iso, more sensitive and quieter shutter release and much faster focussing. He reckons the battery is longer lasting too.
You will need to check the default sharpening, his was set at -3!
Another plus is that there is a battery grip available for it.
If you need to know anything more specific, ask away and I will have a word with my Dad, but he is very impressed with it.
Allan