I’m using the Fairphone since end of last December as a workphone, without any problems. But as with any device from any vendor, you may have some faulty devices as well. What I have heard and read, most people who had issues got their phone fixed or replaced under warranty without problems, except that for some time the support needed long to reply due to a backlog.
But basically your question has been discussed in several threads, just search or browse for it. For example here: