I've eaten at quite a few sushi places including ones in Japan. Shimogamo is easily in my top three in Arizona. I rarely write reviews - but this place deserves it. Fresh cuts of fish, excellent service, great atmosphere & decoration in the restaurant.
This places has a certain level of authenticity that you simply don't find in Arizona (ie. don't look for it at Ra or Stingray). The sushi was crafted with care, the ingredients were of good quality, and they are inventive with certain rolls with out being ridiculous as you'll find with many places catering to more Americanized pallets.
Aside from your usual favorites, try the escolar nigiri and the izakaya style appetizers (sort of like Japanese tapas). I was impressed, and I thought the pricing was right (we paid about $32 + tip ea for two ordering 6 dishes total with beer). The value was definitely high.
I will definitely be going back.