Where do I even begin... I had a chance to use it in 2 different companies, in one of them, I chose Teamtailor and implemented it myself, terrible experience, learned from my mistakes (e.g. to migrate our candidate database, they told me to do an excel file with all the data from our previous ATS. It was so much manual work even though our data team helped with all the excel automations, then they told us the migration will be done in 5 weeks. Since we didn't have that time with our previous ATS ending the contract, I went to OUR engineering team crying and they migrated all the database without manual work in 3 days via APIs...). Of course they took the money for the migration they didn't do, even though they didn't lift a finger, but it was in the contract :)))
What bothers us the most is that their releases don't resemble the best recruitment practices. They're focusing on releasing features that bring no value instead of fixing the ones they already have (eg. Easter hunt or adding raindeer horns to employee pictures...).
Another good example: They have a smart scheduling feature, looks okey-ish, BUT when candidates are selecting time, they need to manually change the timezone (which most of them don't, even though we note that in our invitations), and then they mix the time up.
Also, the platform's performance is terrible, it loads a long time, crashes very often. Adding job postings and interview kits are so buggy it wastes hours.
Their support team can only offer workarounds to fix all the procedural problems. We currently have so many workarounds that we might have chosen a more expensive ATS because all the surrounding systems that we need to use add up to the same price (e.g., Calendly for smooth interview scheduling).
It's just a few frustrations we have, and we're not even that big (100-200 people). In my previous company we were 800, that was mega frustration for the whole hiring team. Review collected by and hosted on G2.com.