We interviewed a bunch of people who were leaving Qualcomm and they describe a bizarre culture where engineers are very, very siloed. Like instead of a board or a body of firmware, individual people might be responsible for one small function for the entirety of a development cycle. It seemed kinda weird and I've never seen anything like that. (But I didn't see this firsthand--just hearsay from people who were leaving or who got cut)
QC culture is indeed extremely siloed, but it is much more collaborative than top-down. You will become very experienced in managing both sideways and up, from positions where you have no authority but need to get stuff done. Managers dictating orders down the chain is now how work gets done; rather, suggestions and guides are placed and "grassroots" efforts are garnered to make things happen.
The base salary is low; both for the market and for San Diego. But, the benefits package is outstanding; really top notch. Absolutely do not undersestimate its value.
QC is not a place to set roots, but it's a great stepping stone. My best advice: take the job, but when you leave, get COBRA and take the insurance with you, because you won't find a suitable replacement elsewhere.