I have never had the sushi here, my review is based only on my Korean food experience at Maru.
It doesn't compare to Mom's cooking, but it definitely satisfies my Korean food craving on those nights when Chinatown is just too far. The interior is very nice and always clean when I have been here.
I usually order:
-pajun (kimchi pancake)
-seafood soondubu (spicy tofu soup)
-dolsot bibimbap (hot stone bibimbap)
Servers are friendly and the food is consistent. Banchan has been fresh everytime as well. Until there are more Korean options in Summerlin I will definitely continue to come to Maru, and even then, keep it in my rotation.