Sumo's a reasonably new Japanese all you can eat restaurant. You make your order on an iPad and it comes out! Easy!
I went here once with my girlfriend for dinner. When we entered, it felt like the waitress that seated us really didn't want to be there. She sat us and someone else had to get the iPad ready to go. I didn't see her the rest of the night so maybe she was finishing a shift or something. The younger fellow there was very pleasant though so that was nice. He made sure to ask if we were full at the end too, which I like.
The food itself is good quality. The tempera batter was very crispy and the sweet potato/broccoli (was very happy to see this one in particular on their menu) were cooked well inside. The udon's alright, but the cutlet inside it really isn't impressive at all. It's like it was soaked in there before it came to us. Would prefer a plain udon in this case. The chicken cutlet was also great - not dried out with a tasty outside and good sauce. Also worth noting is that the mousse seems to be very popular. My girlfriend had ten of these by the time we were done. I was very full by the time I left. Nothing I'd call "mind-blowing", but all still good!
Edit: Something worth noting is that they're constantly upgrading their menu by adding items, which is extremely nice to see. I've been here a few more times with family and/or friends now.
They're currently having their 10% off promotion when you use cash (as of December 2015). I believe the price before that is $27 for a weekend dinner per person. At the discount, it's worth it. Only thing is they don't really advertise the promotion - it's not on their windows or any site. I'm sure you could phone and ask.
All in all, this is definitely a place I recommend going to if you're in the mood for Japanese food. Most everything there is well made and the service is great for the most part.