I went here for an A's playoff game against the Detroit Tigers. This is not what I would call an aesthetically pleasing ball park. I've seen a lot of MLB stadiums, and this was one of the most disappointing. It was like a concrete jungle. Also, I didn't think the A's fans were exactly some of the most polite or friendly fan bases I've encountered.

Bonus: the BART system takes you right there from San Francisco (which is where we were staying). At least that's very convenient.

We went the other day for the Raiders vs Steelers game. As an Aussie tourist this was my first ever NFL game. The stadium was OK but the queues were not. We arrived an hour early and we still did not pass through security in time to see the kick-off. We had a hell of the time finding the pizza as it was not served at every outlet ... it was eventually right down the bottom. No queues for toilets was a bonus. Easy access to the BART stadium was helpful. Decent view even from the nosebleed section!

We were there for a NFL game, and our experience should be interpreted under such experience. First. I understand the need for security in the access, specially since the outburst of violence in the SF-Raiders game last year, but this has to be handled better. The line extended for three or four hundred yards. Access was like passing through airport security, it took an hour and a half and the game was started when we finally got through. Been in many stadiums (some much bigger, like the Aztec Stadium in Mexico City) and access was never so slow and cramped.
Venue is good enough (toilets are awful). The second problem was during exit. Since besides the parking lot, most of the audience went to take the BART, the line there was a human nighmare. We waited, again, for more than an hour just to get enough breathing space to go through.

I have heard that this isn't one of the best stadiums to visit but I have to disagree. Sure, it's older and there are many newer, better places but this isn't all that bad. True, it's not in a great area and there actually is barbed wire on the fence at the entrance over the railroad tracks but this is still a nice place to catch a game. I caught one at night and during the day and found myself pleasantly surprised. Easy to get to via BART or if you're a local and in the know, some close free spots near the park. Nice food selection.