TL;DR: Google is extremely hard to get into (Only 5000 out of 3 million make it), but well worth it. Although only 1% of Qualcomm employees are Google material, I'd highly recommend coming here if you can crack the interview.
I left Qualcomm a few months back when the work environment became too toxic. When things started going south I realized that I was surrounded by racists and bigots and didn't want to work with them.
I joined Google about 3 months back as a SWE. I got a 160% increase in my net compensation (because of a very hefty stock grant). I was a Senior Engineer at Qualcomm and the pay I am getting right now is Senior Staff Engineer's level or higher. On top of this I got a 100k signing bonus (this is not standard but I got this because I had a competing offer from Facebook) as well. The benefits are extremely good, best I have seen or heard of so far.
Prepration:
Google wants people with very high raw intelligence. If you don't have it, you won't make it regardless of how hard you prepare. I have a strong CS background but still prepared for 3 weeks. Know your math and algorithms. Read Steve Yegge's post "Get that Job at Google" for more information and preparation tips. Based on my observations I can say only 1% of Qualcomm employees are Google material.
Interviews:
Phone interview was medium in difficulty. I solved one hard and one medium difficulty question.
Extremely hard but very fair. I went through a phone interview then 5 interviews onsite. You should be able to solve at least 2 questions per interview correctly. Questions are medium hard to hard in difficulty. One of the interviews was high level system design.
The process makes sure that there is no bias or cronyism in the process. Interviewers write an essay about your performance and you are rated on a scale of 1-4. If your score is below 2.7, you are immediately rejected. If it is over 2.7, your file is moved to hiring committee. Hiring committee (HC) is comprised of senior Google engineers who are randomly selected from a pool of engineers. HC members go over the feedback. The HC convenes and each member presents their vote and rationale for hire. If most of the members agree, it is a hire. The file then goes through a bunch of other approvals (Compensation review, VP review, SVP review), You can be rejected at any stage but HC is usually the biggest hurdle.
Working at Google:
The place almost seems magical. Code is extremely high quality and my co-workers are extremely bright. There is no comparison between Qualcomm and Google employees, Google engineers are brilliant. There is very little politics usually at high levels. Promotions are similar to hiring, data driven and makes sure that there is no nepotism.