I like that it's easy for our website builders (that we have in house) clients can easily integrate with this tool without any issues, which also gives them access of getting help when needed from developers at an affordable rate as well! Nothing much so far but i'm sure everything will be great once they start using us more than just one time - if you're looking into integrating your product/platform then try talkjs first before making final decisions because there are some things about these products may seem weird sometimes due to lack awareness yet after reading through documentation all get sorted out :) Have not used other messenger APIs such as whatsapp etc., hence cannot comment how good would work compare to those platforms since haven't tried anything like that.
Integrating simple application was no issue whatsover due to ease useability provided by developer friendly features offered here.