I'm currently using my GA645Zi whilst on a touring holiday in Italy, and my thoughts are as follows:

Pros:
- In AE mode(s), operation is very quick
- Being 645 format you get 16 shots per roll (as opposed to 12 with 6x6)
- Relatively light
- Very quick & easy film loading
- I find the ergonomics & handling quite good
- Built in flash (only activated when raised and needed!)

Cons:
- Limited manual operation which is not that easy to use
- Manual focus operation is difficult and I haven't used it yet
- Limited zoom range (I would have liked a slightly longer range at the long end)
- Would like more control in P mode (ability to change speed & aperture combination)
- Slow lens (fine for external shots but limited internally without flash)

Overall, I feel that the GA645Xi is a very good choice for travel, especially when you don't have time to set up and work out exposure as you would with, say a fully manual MF camera. In fact the operation and handling is on a par with a 35mm camera, but with MF quality.

(The lens is slow so I have my Rolleiflex with me loaded with fast film for interior shots)