Got my new camera. It's a little thinner and sleeker than the old F10. My first concern was the battery life. The F10 was rated at 500 shots, the F40 is only rated at 300. I shot with it all day Friday. Then I filled the memory card shooting the John Mayer concert with it Saturday. Then I shot 74 pics at Em's sister's 3rd birthday party on Sunday. Sunday night battery was still indicating full charge. I don't think battery life is going to be a problem at all.
The face detection software works fairly well. In a group of 6 people it detected three faces, but that was enough to keep everybody in focus. It's especially useful for setting the timer and running into the shot because it refocuses on your face once you're in the shot.
The various scene modes work well. I used the "beach" mode for some bright pool shots on Sunday and it kept the reflections off the water from washing everything out. Hopefully it will work just as well with reflections off sand.
I've put the camera into the underwater housing and tested that indeed all the controls are still functional through various levers and buttons. However, I still haven't given it a submersion test. It's kind of scary to just submerge your brand new electronics. The housing is going to be a definite plus just for the beach though because the sand gets in everything. I'll finally feel comfortable carrying a camera around. The only downside to the underwater housing is that there's limitations to when you can open it back up. If you have it in salt water you're supposed to soak it in freshwater for 30 minutes to dissolve all the salt off of the hinges before opening it again.
I'm really happy with the performance of the camera, and I'm really happy that Fuji finally let me use an SD card since every other device I own uses these cards. However, what's up with the specialized cords? On the F10, you couldn't plug it directly into the computer. You had to have the little Fuji break-out box to then plug a USB cord and charger into the camera. With the F10 there's no break-out box, but it's not a standard fitting USB cord. You're also not supposed to charge the battery in the camera. I really liked just plugging the camera in, so it was charging while transferring pictures, etc. Why doesn't Fuji use a standard USB cord?!!!
Other than that, great camera. I highly recommend it.