It is a very stable solution. I prefer using it over Concourse. I have only experienced one scenario where a server had gone down due to configuration changes. Other than that, it has been stable and reliable. 

The solution works quickly, and I haven't noticed any issues with stability; however, I haven't tried to test it out either. 

Have not experienced any "failure" of TeamCity.  An occasional lack of responsiveness from the web interface happens from time to time.  May have been appropriate to provide more CPU resources when the VM was originally created.

The solution is reliable. I don't recall bugs or glitches. It doesn't crash. It's stable.

This is a very stable solution.

No, it stays running and performs build regularly.

It seemed a very stable tool with hardly any downtime in the six months I was using it.

There were no issues with stability.

The initial setup was straightforward. I can log in and start working as soon as I have my account credentials. While some advance training is needed, the person would be good to go once he has mastered the basics. 

We had to add additional servers to enable a failover capability, but this was more to do with our infrastructure

No issues encountered.

We did not encounter any serious issues with stability so far.

No issues encountered.

No issues.

As versions progress, TeamCity has greatly improved it's stability with it's resourcing. Also following JetBrains' documentation about how to set up TeamCity, distributes load in a more even fashion.

Never ever had any stability issues.

No issues encountered.

Depends on the server host, but it runs on Java so it needs high specs. Otherwise, the website takes a long time to load. 

Also, supporting newer technologies is limited.

Generally no, just in a few cases.

In the prior version, there were some problems with the doc agents, but the latest version is quite stable.