I know a lot of entities that have given up on Twilio. Here is why:
1- Twilio simply does not work on web based external-consumer-facing implementations because WebRTC is still an emerging standard and is not supported by all web browsers. It can be great for internal company intranet or application specific use cases but not if you want your existing and potential customers to be able to call you from your website.
2- It is complex to stich all the features together for twilio integration. They do offer extensive knowledge base on their website because you have to go through and understand a bunch of technical documentation before you can play with twilio API. Most companies want to focus on their core business and not VOIP technology related integrations.
3- Support is hard to get and comes when the damage has already been done.
4- Lack of Analytics on calls, who is calling, etc.
I'd recommend you look at Click-2-call API made easy before you make an investment decision.