Communicator 4.51 is a substantial upgrade from Communicator 4.0. With Smart Browsing, Instant Messaging with group chat, a redesigned Messenger component and Real Network's RealPlayer, the complete version of Communicator 4.51 is about the same size as Communicator 4.0.
In the end Netscape still has some minor drawbacks when compared to Internet Explorer 5. It lacks the full-screen feature of Internet Explorer, and its bookmark display is still somewhat primitive compared with Explorer's, along with some other minor problems. But no matter what browser you use, it is definitely worth checking out.