I also work for a hedge fund, so I'll throw out an answer. It's a 3 person shop focused on algorithm trading, the founder and two employees (including me) managing the money of the founder.

I'd say a good 50-75% of the work is tricky quantitative programming. Read: prediction, analysis, concurrency, micro optimizations (today I shaved 10-20 seconds of a 15 minute program run time). Probably 10-15% of it fits what you would describe as "far out, complex coding". There is of course grunt work; tax calculations, making our FIX talk to their FIX, etc. There is a lot of frustration; I've had a number of ideas I liked, all of which failed horribly.

I'd say it's roughly equivalent to being an employee at a startup, except that there are only 3 employees, all of whom are within shouting distance.