Check the papers and mail outs because they always have coupons and the coupons are great... generally you can find buy 1 get 1 free lunch and dinner coupons. Their already great prices make it an even cheaper date!
Their food is authentic. If you're expecting Spanish Rice like you get from the Lipton Bags you're in for a surprise. Not at all 'hot' and spicy as one expects from Mexican dining. Everything is made on the spot, comes out hot and is most always quite awesome. This is also a great way to try some new, authentic dishes.
The only 'set back' is that there is a slight language barrier sometimes but generally they have someone handy that's very bi-lingual. Great service. Great food. Great prices!