arXiv is just a repository for papers to make them available before they are published/peer-reviewed. Just because a paper is on arXiv does not make it bad, but it doesn't mean that it is high quality either. Typically the people in the field will know which papers are important.
It's not bad, there are just some gaps. I expect a follow-up paper which explains everything thoroughly. I feel like my masters thesis should have started after that paper.
