I, as well, just returned from a two night visit to the Oakland City Center Marriott.

Observations:

Good:
1. Internet speed was very fast when tested. 100 up and down. This was enhanced internet access, as I have free service via Titanium status.
2. Hotel condition. Well maintained public areas and rooms. Clean and updated.
3. Status recognition. Was good, given upper floor in corner room. No suite upgrade, but they were shown as sold out night of arrival.
4. M Club. Good, not great. Food spread reminds me of standard US concierge lounges of old, OK breakfast and OK evening snacks. Pastries in morning were OK, not stale but not quite great either. Not close to offerings at MClub at Marriott Marquise in SF.
5. Transit access to SF. Easy and close access to BART station. Safe ingress/egress to station night and day. $3.50 OW with Clipper card to SF in 15 minutes.
6. Uber/Lyft access to OAK airport. About $18, which isn't bad.
7. Hotel staff. Courteous and helpful. Had solid security at every entrance to manage non-customer traffic flow.

Not so good:
1. Neighborhood. I've lived in urban environments and I didn't feel comfortable on the streets here. When we went out early one evening on the weekend for a few blocks walk, there were a number of folks standing around that didn't seem to have anything in particular to do. Not a lot of foot traffic. You can see efforts to spiff up place but still not somewhere I want to hang out in. YMMV.
2. Street people. Other posts mention walking to Jack London Square, which you can see in the distance from the hotel. You can certainly walk there, but you have to walk by a significant homeless encampment under the freeway overpass to get there. No thanks.

I've stayed at this property several times over the years. Not a bad place to set up a base camp for hanging out in SF via transit, because of a very significant difference in cost.

jb