I've been to Si Senor 3 times since I moved into the West Park neighborhood. The first two visits were pretty standard- food arrived within about 10-15 minutes and it tasted about the same as all Mexican food. I'll be honest- I like Mexican food, but most of the dishes taste similar to me and there isn't one restaurant that stands out from the rest. It's all the same to me.
Prices seem a little high at Si Senor.
On Monday, I went in with a group of 8 (including 2 children). We were seated pretty quickly and addressed by several servers. it seemed like they were serving our table as a group, which you would think would get us faster service. However, there were times that we didn't see anyone at our table and couldn't get refills or anything. The food (standard food, nothing special) took 35 minutes. Everything was accurate, but it took much longer than most Mexican restaurants. It was hard to get refills and our checks. We were at the restaurant for over 2 hours.
I will say that the Baja tacos were delicious. The fish was fried to a nice crisp and I like the slaw that comes with them. Add a nice squeeze of lime, ask for a side of shredded cheese... and you're in taco business! Delish!