It was a combination of things. I didn't enjoy the work environment very much and I thought some of the policies were rather dumb. The product itself was ~8 years old and had just been hacked on since then.

The Big Thing was when, after I had been there 2 months, they announced benefits cuts for my subsidiary -- and no bonuses. These benefits were very important to me and I had stressed this during my interview. So that turned me into a motivated job seeker.

I kept my resignation as professional as possible. Worked out my time, did a proper knowledge transfer, wished everyone luck.