There are three Oni reviews up at GamePen (score: 3/5), Mac Gamer (score: 4/5), and MPOG (score: 4.5/5). GamePen gives appreciation to Oni's attention to detail with audio, describing the joy of getting a more realistic experience when cracking opponents' necks, but picks on the lack of gamepad support and trashes Oni's AI. Mac Gamer appears to give a somewhat more even assessment of the game, however:

The challenge, however, is to judge Oni by what it is; not by what it could have been (or even what Bungie once upon a time promised it would be). When judged on its own merits, Oni delivers a hundredfold. When compared to the list of would have, could have, should haves there is no way any game could deliver. Don't be one of those people who only dwells on what you didn't get.

Rating: 4 out of 5.

Pros:
- Totally fresh combat style (finally somebody came up with some)
- Beautiful artwork
- Downright brilliant weaponry
- Awesome physics
- A really nice break from first person shooters

Cons:
- Lack of multiplayer comes close to killing all replay value...
- ...As does the lack of editing tools.
- Some simple stuff like in-game control editing was oddly forgotten.
- Requirements a bit stiff for most users.
- Wayyyyy too long in development.

Oni also takes a hit from MPOG for what is described as a lack of replay value, and a questionable overall value for around 20 hours of gameplay, but they do reassure that there are much worse ways that one could spend one's coin.