If you like model railways then this is the museum for you. My Husband has his own model railway at home so we had to visit this museum. He got lots of ideas for adding to his own layout.
There are loads of different layouts of different gauges from the very large to the very small. They are also planning many more for 2015 so you can see them mid construction - which shows non-modellers how they are constructed and gives existing modellers ideas too.
There are some areas designed specifically for kids - which keeps them entertained and out of the way of the grown up visitors - excellent.
My only advice is to avoid free Tuesday. From what we could gather the museums in the park are free to San Diego residents on certain Tuesdays each month - the day we went! - which means the park and museums are absolutely packed with kids! Less so with this museum though as they were all in the kids model room.Worth a trip.