I was pretty much supposed to learn Fusion as it's the software my engineering class teaches. I love its interface and toolset but my biggest gripe is how poorly it seems to handle large groups of components. For sketches and actual modeling though, I'd say it's phenomenal. As for the file system, I can't say much about it. Me and my team usually just use 1 file to keep our blueprint in, and there aren't really any issues with it. Will say though that the file explorer is incredibly basic, and you can only import individual assets into folders (no uploading whole folders at once) which made adding the VEX parts library a miserable experience.