I used SpyGlass and find the tool quite useful and the UI very intuitive. It certainly finds less links than AHrefs, but still it's a good software to have, especially as it is free AppSumo deal. I like link analysis and risk evaluation, it was correct in over 80% of cases. Was very easy to mark links to sanitize and generate disavow file. What I didn't like is the following:
1. Auto installation of upgrade without asking users to approve/confirm. This is a very dangerous practice as it allows to bypass Windows 10 security. Even if you validate the original piece of software for malware and let it run, you have no idea what it downloads during the upgrade.
2. This is more about WebsiteAudit software rather than SpyGlass: they should really introduce the delays when crawling the site. Half of my links returned 503 because the bot crawling the site was making too many hits per minute and was eventually blocked by security software.