Rumbi is conveniently located right by UNLV so it's already a plus in my book. I've gotten Groupons here before, so I've checked it out a few times.
I don't think you can go wrong with a rice bowl. The rumbi rice is excellent and both their chicken and pork are great with the rice. I've experimented with some of the sauces, like the spicy Hawaiian and I haven't found one I didn't like. The $8 you usually pay with a rice bowl scares off some folk, but I think for the quality, it's not asking too much.
The customer service is always excellent there. The staff is very concerned with making sure you have all your needs met. I've had the manager introduce himself and actually take my order. I like the effort that is put into meeting the people eating your food. Shows that you care and want people to come out.
I will say that last time I came in to eat, the food came out quicker than it normally does. It wasn't as fresh as some of the other times I've had it. Just brushing that off as an anomaly as normally every time I eat there, you can tell they just cooked your food.
Rumbi is a nice diversion from the standard fare they have around the university and it should be one of the places to highly consider if you are trying to get some decent lunch.