I have both the GA645 and the Zi. I like both but the zoom range is quite limited and the slower lens is a detriment on the zi. Bought the zi out of curiosity but will likely keep my GA645 and sell off the zi. Some repair people report the electrical ribbon at the base of the back door as a weak point that frequently fails as the back is opened and closed many times over time. Once it goes that's it, no parts other than cannibalizing another.