I think you should be able to filter by keywords or number of stars. And why only the author can comment on reviews? I think anyone should be able to comment on reviews. If you want to change your review, you have to delete it and then do it again, I think it would be cool if there was an edit button. You should be able to like reviews and review comments.
I do think the review system needs to be reworked but making it open for anyone to comment on other peoples reviews is just stupid. The only thing that i think needs to change is the amount of stars mods get for the quality they are, especially lately. Single simple config packs are not worth 5 stars, same goes for basic "fps" maps (I'm talking about you @gigawert). We seriously need to raise the quality benchmark that is placed on mods that want to be accepted to the repo.
To be fair, the FPS map was just a side project. But on the other hand, have you ever tried to make a high quality terrain texture yourself? It is not easy at all in BeamNG.