I stayed here 4 times in 2015 all as a gold member, so here's a (limited) review as well. All of my stays were one night stays after having stayed in San Francisco and then flying out of OAK the next morning.

Shuttle - The shuttle ran every 20 minutes during the times I needed it, between the hotel and the airport. It was reliable, the ride was only about 5 minutes, and the shuttle was direct, not stopping at a bunch of other hotels. It also stops at the BART station (Coliseum) ONLY at the top of the hour, and after having called the front desk to request it. This makes it a bit less convenient and a bit more expensive when you're arriving via BART -- you have to pay an extra $6 on your BART fare to ride the connector between Coliseum station and OAK, which takes 8 minutes plus wait time.

Room - I was upgraded as a gold to a suite one time!!! One time I was told that a regular room in the main building, where the front desk is, was an upgrade. Two other times I was not upgraded. The rooms themselves, to agree with the previous post, were "satisfactory, nothing special - dated but clean and functional."

Breakfast - As a gold I received a voucher for full buffet breakfast in the restaurant. The buffet was somewhere between average and good -- nothing particularly memorable, but better than some. And certainly better than those San Francisco Hilton properties that honor the breakfast benefit only via "grab and go." Hilton OAK had the usual spread of scrambled eggs, bacon, sausage, shredded potatoes, fruit, pastries, etc.

Miscellaneous - I was recognized at check-in at each time as a gold member and the bottles of water were always waiting for me in the room. I didn't have complaints about the area itself because I never left the hotel grounds except via the shuttle. It's not really an area that lends itself well to walking around. It's great for one night stays when you're using the airport. For multi-night stays where you're wanting to get out into the area, I'd recommend instead the HGI San Leandro, which also has an airport shuttle to OAK, a BART shuttle, and is walkable to BART and other things in a not-scary neighborhood.