Mona Lisa is by far one of my favorite restaurants in San Diego. I've been going there for about 13 years, and one of the main reasons is the tiramisu! It is the best. I don't think it has any kahlua at all - I think the sponge cake is just soaked in espresso. And that cream cheese! Oh my gosh - literally to die for!
If you go during the week, you can pretty much get seated right away. If you go on a Friday or Saturday night, I'd recommend going early or later in the evening. Many times I have waited around 20 minutes or so for a table, so plan accordingly.
Their food is pretty good. I usually get the lasagna marinara (sometimes the cooks add onions, sometimes they don't - I like it without), or the cheese raviolis with marinara sauce. My fiancee will get their meat dishes, and thinks they're pretty good. Their dinner salads are simple but good, and I love their minestrone soup, though on occasion it has been a bit bland. A little salt usually helps.
The service (most of the time) leaves something to be desired. Every so often we'll get a great waitress, but more often than not the service is a bit slow, and you'll realize you've been sitting there for 10 minutes or so with a drink just waiting to be refilled. However, the food and reasonable prices usually make up for this, and I generally try to go by there now whenever I'm in San Diego (recently moved to LA).
Pros: AWESOME Tiramisu! Reasonable prices.
Cons: Parking, Occasionally service is slow