I love being able to bill my clients in-house to use out services without paying extra fees or waiting hours with external carriers. It allows me to save money and give them accurate invoices before they see any cash flow issues within their account! No issues yet but it's a good feature to have if you're already using Billrun. There are no built features currently which would be nice like creating custom reports for specific purposes when needed. If it were priced better, we'd probably look at moving away from internal billing because it could lose us customers to lower pricing with an outside carrier - but not many companies will sell you what you don't want so thats something. We also have some reporting requirements around our business we need to perform internally when we aren't allowed to do this through the carrier (like when we change phone numbers I like that everything is automated, no manual entry needed. My only dislike is that it can be costly in terms of price. It would be nice if they could lower the cost so more people will use it. Overall it has been great! There isn't anything that I dislike about this system. It has helped us in making our job easier. It has also made our accounting process easier too.