Here is my thought on this. It could be awesome...it could be terrible.
However, if I was just going to play the optimist, look at it this way. J.J. Abrams has an amazing visual eye and directing style, but frankly, his storytelling is mediocre at best and kinda sucks at worst. Tarantino on the other hand has an amazing visual eye, and amazing story telling talent. His scripts are tight and full of interesting dialogue and Star Trek is at its best with interesting dialogue.
Also, the people who can't think past their noses are already talking about how a Tarantino movie would be bloody, full of f-bombs and have racist characters using the n-word. But just think about that for a minute and realize how silly that argument is. Directors are creative people and therefore can branch out into different ways of doing things.
Remember when everyone said that Justin Lin was going to turn Star Trek Beyond into Fast and Furious in space? Now we know he didn't. Many fans, myself among them, think Beyond is the closest in feel to TOS. Yes, there is that one motorbike scene, but it's complimented with scifi in the form of holograms and crystallizing gas.
Look, I have faith Tarantino can tell what is appropriate for Trek and what is not, and use that judgement to not put his style on it TOO much. With him coming up with most of the story/dialogue, and Abrams lending his talents as a visual eye...we could be in for a treat. Or a disaster. Who knows?