Pros
If you want to live in San Diego, this is more or less the biggest game in town if you're a software developer (or - better yet - a hardware engineer). The commute is moderately tolerable - even if it sometimes takes more than an hour to get to work from downtown San Diego - and the benefits are decent. It's kind of like working for a solid B-list company in Silicon Valley.
Kontras
QUALCOMM seems to be infested with employees who essentially got lucky: they somehow stumbled into a position with QCOM back in the early 1990s and worked their way into a more prestigious position with big cash prizes, stock grants, and so on. Sadly, this means that as a new hire you'll be faced with an impenetrable old boys' (or girls') network: as an outsider, you will never, ever be promoted. Many employees are minimally competent at best, and the company has embarked on aggressive cost cutting measures, so be prepared for a lot of offshoring hassles (think 6am meetings with India) as well as deep disconnects in terms of cross-cultural communication and technical competence.