I'm giving Masa 5 stars for value, quality and consistency. This is one of the few places in Boston that my wife and come back to regularly.
Masa's main menu is reasonably priced and is always well executed. The flavor combinations they offer and the ingredients are unique and so delicious. My wife and I ate dinner their last week. I had the halibut dish which was awesome and my wife (vegetarian) had the Roasted yellow pepper, filled with a wild mushroom and quinoa salad -Roasted Cashews, Stone Ground Corn Polenta, Pomegranate Molasses which I also thought was delicious.
We've eaten brunch here several times as well and always love it.
We come to the bar all the time for the $1 tapas which are $.50 4-7 PM and after 10 PM (insane!). The drinks are great and the bartenders/servers are really friendly.
My only request would be if they could upgrade their wine glasses from the cheapy small glass that you get at wine tastings to full size glasses which allow you to fully appreciate the wine.
All that being said I would recommend Masa to anyone in a heartbeat.