Those who know Nikon's lineup well, will know that this camera falls between the flagship F5 and the high consumer end N80. It has a tough role to fill, and it does it perfectly.
The focusing on the F100 is far faster than on the N80. When I originally bought my N80, I thought it was fast. On the F100, it's amazing. The images from the F100 are great, and I've never had one that didn't turn out because of camera error (what can I say, human error is the prevalent error behind this camera)
This camera isn't for everyone though. It lacks some of the features of the N80, such as the pop up flash and the grid lines on demand. If you're looking for an introductory camera, this is not it.
However, if you're serious about photography and already have a speedlight (flash), then this camera is definitely worth it. The reason for it not including a pop up flash is that the camera is geared towards very serious amateurs or professional photographers. Nikon figures that by the time you step up to one of their higher end cameras like the F100 or the F5, that you've already acquired a good flash unit. To put it into perspective, one of the photographers who routinely shoots at the local high school shoots with this camera. You can get the grid lines in the viewfinder by spending another [amount of money] and replacing the screen inside the viewfinder. Unfortunately, they aren't built in like the N80, but there is a work around, so in my mind, that's not a big deal.
This camera also has a vertical grip via the high power pack, which is something that the N80 is clearly lacking. So if you tend to shoot a lot in the vertical direction, this is a definite plus, especially if you're like me and don't have very big hands.
All in all, I highly recommend this camera for those who are serious about their photography, and don't want to spend the cash for the F5.