Not sure about Peer1 SJC but Peer1 NYC was not bad. Network and Support are top notch. I never called at night but during day time, anything from VLANs to rDNS records were immediately taken care of over the phone, no tickets or emails.
I felt cooling was sufficient only in the aisles where the CRAC was blowing cold air directly into. Other "cold" aisles were actually warm, but bearable.
Racks are too narrow, they fit all types of long and wide chassis, example Dell PE1950, but you have to jiggle a bit at the rack ears to fit it. They could have made the cabinets a bit wider.
If you are planning to go with anything LESS than a 1/2 rack, the 20amp circuit is shared between 2 quarter racks. So a lot of times the 1/4 rack guy above me use my power allocation, which was very annoying to deal with.
I never experienced a network or power outage in their facility and they notify you well in advance about regular maintenance. Thats a another positive thing, they regularly maintain and service their equipments, which most datacenters ignore to do.
Overall we were happy. The only reason we had to move out of there is because of the commute into NYC.
Now mind you, all this Peer1 NYC, not sure what SJC is like, but I'm almost certain its similar.