Service: Good, very quick at refilling chips as soon as you get low. Chips and salsa were actually already set at the table for us when we were seated, which was nice - kind of makes you wonder how long they sat there though.
Food: Fish tacos were bland. Quesadillas are extremely lacking. Don't bother with them as you can get a better one literally anywhere else. Guacamole looks like runny green poo. Other items I've tried tasted pretty standard - not stand out or especially delicious, but edible.
Ambience: Large restaurant, always somewhat busy for lunch. Feels a bit dingy though.
Verdict: Mediocre. If you're not set on Mexican food I would suggest going next door to Cornish Pasty Co instead.