Yes, it is totally acceptable within Japanese culture to enjoy your sushi using your fingers, however, where I'm located the normalized standard is to use chop sticks, even at traditional Japanese sushi places. I try to match the etiquette of the general group, and when I look around, even at the more traditional places where most of the customers are Japanese, no one uses their hands for the sushi, though most do for things like tempura. If you look at the more traditional sushi offerings such as sashimi, maki with the nori on the outside of the role, or nigiri, I can understand that these were definitely originally finger foods - they're neat, compact one or two bite affairs.
Locally we have a very vast variety of sushi that is drastically different in style from traditional Japanese sushi though. For example, there are several Korean sushi places that have gained major popularity where I live, and at these joints the focus is on saucy and considerably un-finger-friendly maki rolls. A lot of westernized or fusion-style sushi that I encounter is also clearly prepared to be eaten only with chop sticks and it would be unappealing, messy and frankly unhygienic when eating from a shared plate to use one's hands for a lot of the maki I encounter these days.
Here's a nice little thread on
Chowhound about the fingers vs chopsticks conundrum