What intrigued me about BOLT (which is in a beta version at the moment of this writing) is the fact that it is written in Java (Java ME). It is designed for entry-level phones (with MIDP 2.0 and CLDC 1.0 or higher), but certainly it runs just fine on smartphones too. It is considered to offer fast and secure web browsing. How secure? 128-bit SSL Connections, filtering done on the server to protect you from malicious code, certification error notifications, and pop-up blocker. How fast is it? Reports have mentioned that on a Nokia 6120 (which runs on the S60 platforms), BOLT loaded the phonearena.com website in 14 seconds, while the built-in browser loaded it in 40 seconds.
If you are looking for screenshots (and further test results), head to phonearena.