I'm a frequent visitor of Sakana. My wife and I love it. Prices are better than average (during happy hour). Portions, while being only 5 pieces for happy hour, are stuffed full.
While nearly every visit leaves us satisfied, the last couple of times haven't been nearly as good. It might be the new wait staff, or that we just got a not-so-fresh batch of fish on our plate. If my last visit had been my first time at Sakana, I probably wouldn't have returned. However, since the majority of the time the food is a B+, and because the prices are good, I'll continue to come back.
The joint is small, and the hours are somewhat goofy (close around 2pm after lunch and re-open up at 5:30 for dinner), so come early on and plan accordingly.