I can't say that Viy 3D is an adaptation. It is a story which uses Viy legend just as background. And this is the first problem with the film. When you talk about Viy, you talk about fear. The legends are about that, Gogol's story is about that, 1967 film is about that. So how can a film, which places Viy in its title, and even mentions Gogol story, just throw away this spirit of something unknown and frightening, and instead suggest some stupid explanation for the story and challenge the existence of Viy.
Another problem of the film is its ugly propaganda constructed from old clichés. Orthodox church is for enslaving people (wow, have you seen this 'new' idea before?), ukrainian сossacks are drunk and live in dirt, the English scholar is smart and can handle everything. In general you can see the contrast - bare and dirty Ukraine vs rich and beautiful England.
OK, so maybe for someone who doesn't care about Viy concept and propaganda, is this film good?
The story in film is very similar to Sleepy Hollow, but is worse. Plot doesn't offer something new, but fails to provide some solid story. It is a mess without any reasons. I can recall the most effects-loaded scene of cossacks transforming into devils and trying to frighten cartographer. Are there any reasons for this part of plot? No. Are there any consequences of this scene? No. The cartographer wakes up next morning and just continues his work. So you can just remove this scene from the film and you don't lose anything as far as plot is concerned. Same for many scenes.
Effects are OK. You can enjoy some scenes.
The film is not scary, there are some exciting moments, but the film never crosses the line of a real horror.
Acting is decent, everyone did a good job.
Conclusions: 1) If you like the story of Viy and want to see some adaptation - the film is not for you. 2) If you want some horror film - this film is not for you. 3) If you don't care much about a new story and would like to enjoy the effects and acting - you can have a good time.