My work life is similar to yummyfajitas. I work in a 4-person fund that was bought by a 30-person firm (collection of different alternative asset funds), which makes us semi-autonomous. I'm basically a jack-of-all-trades there, but 80% of my time is model development. When I first started, the fund was still in its infancy and it was all about creating the frameworks, automating tedious tasks, etc. Since then it's more about statistics, AI, and lately saving pennies.

The most fun is being able to watch the market, and have that epiphany where you all of a sudden have a trading system in mind that you want to try. You furiously code for the next 30 minutes, compile, debug, input parameters, hit enter--- and then have your dreams crushed to find "hmm... well if I traded that, we'd lose 98% in x years." :)

I'd say it's best described as a startup meets online poker. On the startup side, it's a small team, constantly pivoting based on perceived market demands for different investment vehicles, and lots more freedom to fail fast with little ideas. The poker side is where the whole luck factor comes in, dealing with huge swings due to flash crashes and political speeches.