Zen Curry hands down has some of the best customer service compared to a lot of other Asian restaurants in Vegas. While the size of the store makes it feel a bit cramped at times when it's busy, I can let it slide since whenever I eat there I always end up feeling a bit better than when I left.
But let's get to the nitty gritty -- the food. I love curry and I'm not a stickler from where it comes from. Amongst all the places I've tried curry from (Thai Noodle House, Surangs Thai Kitchen, Mt Everest, Shuseki, and various Korean restaurants) I think Zen Curry's is my favorite. The curry itself has a nice density to it and the flavor always stands out. Combined with large portion sizes at a decent price, eating here won't break the bank.
The menu itself is pretty simple (katsu, pork, steak) but they have a large board that has some specials in terms of what meat or addons you can get for your curry.