This case is probably the lightest case you will find, and it is incredibly stylish. For these two reasons, I complete love it! However there are some drawbacks which you may find severe.
Firstly, I don't trust this case to protect my instrument as well as others I have had. Though you shouldn't put anything on top of any case, that applies doubly so here as the shell isn't rock solid like normal wood or fibreglass cases. While it doesn't flex very much at all when closed, I doubt it has a lot of compression strength. This is the price of being lighter.
Violists not having a standard shape, you may have some fitting issues. The corners of the lower bout on my instrument press against the foam insulation, which means it is vulnerable to impact from the sides. This is pretty worrying, more than the previous point.
Additionally, the case case doesn't really have proper suspension. While there is a raised section of insulation, it is one piece with the rest of the case and not soft, which renders it fairly useless. Also, the scroll of my instrument contacts the bottom (even though there is an indent), I use a small sponge to keep it raised.
Overall, I still give it 4 stars despite the issues since I still really like it - perhaps for my instrument which doesn't fit totally well it is 3 stars.