The only portable uses of bitfields are to potentially save a little memory, and to get "modulo-power-of-2" behaviour. Bitfields are a classic "not as useful as they first appear" feature.
That is, if you don't mind tying your code to a particular platform and compiler. The alignment and packing of bitfields is implementation dependent: http://stackoverflow.com/questions/1490092/c-c-force-bit-fie...
For what it's worth, I use bitfields on occasion, but only to save memory and get better warnings when storing range-limited values. It's nice to have the compiler warn about a comparison always being true or false due to the limited range of a type. The performance of bitfields is probably worse than just tossing all my boolean values into an int32_t or int8_t.