Binance Dex was launched in Feb 2019 so it is relatively new. Since Binance dot com is a centralized exchange, Binance Dex was introduced so that traders can now have the option of trading and keeping the custody of their Private keys.
The exchange was built on Binance chain blockchain which allow it to support similar trading Volume like Binance. Although since it was created its trading volume is in nowhere comparable with to that of Binance dot com.
Another good spot about Binance Dex is the way it handles concepts of takers and makers. It uses periodic auction to match all available orders and that eliminates the issues related takers and makers.
It employ Byzantine fault tolerance (BFT) and proof of stake as consensus algorithm for validation of transaction. And as a Dex all traders and investors can enjoy safer and more secure transactions since servers are spread across the globe.