Dynamic Range. The ability to capture highlights and low light on the same picture. Look at my boots. You can still see plenty of details. Then you can see the clouds in the sky. It's great. Yes, the new D750 or D4s or MKIII will be able to do the same, but compare to my old Fuji X-Pro-1, this is better.
Composition. Every shot I take, cost me $0.75 and I have only 24 shots per roll. It helps me to slow down and thing about the composition of my photo. Is it worth a shot ?
Shooting with film feels so much more natural. You just shot and forget. No editing, no looking back at the screen. I love shooting with my cheap, light, all plastic Nikon F55. I want to live in the present and sink into the moments without having to think about taking pictures.
If I have learn something about life, it is that it is too short. Too short to not have batteries, to have a problem of memory card (or full), to worry because it is raining on your X-Pro or D300s. A film camera is the perfect tool to capture real memories.
Every film shot I have are keepers. I have over 600 film shot in the last year. On 90% of them, there is a story to be told, an emotion to be felt. I cannot say the same for my digital shot.