For an All-You-Can-Eat place, Spring Sushi is actually not bad!
While the quality & variety of the sushi here is average, you really shouldn't expect top-notch quality fish and rolls in an AYCE unless you are paying premium dollar. For the $30 they are charging (as of Apr 2018, plus a few dollars extra on weekends/holidays), you can fill your tummy to your heart's desire at the busiest area of downtown Toronto. It is also a bit cheaper than another AYCE sushi place downtown, which I would not name here.
The decor is nice here with a casual yet modern/clean feel. They also have a huge patio overlooking Yonge & Dundas Square, which I am sure will be hugely popular in the summer.
I was pleased with their aburi sushi selection - it does take some prep work to make and it is nice to see that they offer it. While none of the items they offer will blow your mind, I found that it tastes quite decent for a restaurant of this caliber.
Ordering is all done through an iPad, though a server needs to come by to confirm it before it gets sent out which can be a bit time-consuming. Service for my visit on a weeknight was prompt, but I can imagine it can get quite busy here on weekends.
Overall, I would rate this just a bit under 4-stars for offering a good return on value with decent tasting food.