I don't know too much about them, but would like to hear what others say...
I know that they are divided up into "centers", so Kaiser-SF is the Cardiac center and does all of the caths and CABG for northern california. Oakland is the Spine center and Redwood city (no residency program I don't think) is neurosurg. There are no fellowship opportunities and as a resident you consult attendings, not fellows--this is good/bad depending on who you ask. Compensation is better than other res programs (at least 50k compared to UCSF--something like 38-40k).
A lot of residents are from nor cal, which is why they are choosing Kaiser. They seem like they are very bright and just know that they want a more "laid back" atmosphere to train in. There is always an internist in house, so you have back up if you need it, but it is run pretty much like an academic hospital.
sorry that this wasn't more coherent, just some thoughts...