Also running a moderately large EspoCRM instance here, plus some more hobby-scale ones, and agree with all the points made so far. Generally, I'm a fan. The Advanced pack and VoIP extensions have been good additions and I've not had any issues with the company behind EspoCRM either. Just works, admittedly with a bit of learning curve to administer, perhaps, as has been mentioned, but a lot of that is down to the customizations available. Documentation is only okay for most things, in my opinion. Overall, I'd recommend it