I have to say I have read the other reviews and I can see how it may be hit or miss.
We have been there several times and the food and service has always been good. There are many price points $8.95 to $30+ so Mama Mia's can accommodate most budgets.
We did go there one Valentines day and did not care for the reduced selection "special menu" (common for V-day) and we did not stay.
The reason I like this place is it is off the beaten path and you can find a quiet corner for a romantic date night.