I eat a lot of sushi. A lot. The arguably best sushi restaurant in the US is located in a mini mall. But that mini mall is not in Madison (it's in Los Angeles), and that restaurant is not Wasabi.
I have eaten at Wasabi a handful of times, usually at the behest of friends who promise me that the last time I went and was nonplussed must have been anomalous.
Anyway, the folks there do their best to execute straight-ahead traditional generic Japantown-style nigiri and makimono with little flair and, at times, ingredients of questionable freshness. Each of the following has been problematic on one or more of my visits: hirame (unfresh), mirugai (unfresh), amaebi (really small), saba (unfresh), uni (remarkably unfresh). Even the easy ones like sake, hamachi and maguro have been disappointing. The portions are small, the presentation very mini mall, and the prices moderate-to-high.
The fact that people in Madison - MY people - swear by Wasabi is immaterial. In any larger town or one closer to the Pacific it would be, if lucky, an also-ran. They even use powdered wasabi. Way to disrespect your namesake!
Now let's talk about ambiance. I know I've beaten the mini mall thing to death, but...did I mention Wasabi's located in a mini mall? You can eat outside in nice weather, something I have done and found moderately enjoyable. I would recommend eating outside because the interior is distinctive mostly for its low office space style drop ceilings, bright fluorescent lighting, insipid floor and wall surfaces and paintings that make you wonder if that creepy Patrick Nagel guy from the 1980s tried his hand at painting Japanese landscapes. Please, use good design to distract me and make feel better while signing the credit card slip at the end of a mediocre meal.
If you want to eat something sushi-like in Madison and enjoy the meal, I recommend you walk the extra 10 minutes up State Street and across the Square to Muramoto, a block past the Capitol building at 106 King St. They have a lot better, more imaginative, better-portioned food with the ambiance to match. They also sometimes make the smart tactical decision to not try to include harder to get or fast-expiring fish on their menu when they can create a novel variant on the recipe using something like, say, duck, mango and unagi sauce.