Personal experience with Netzero/Netscape/any that use funky accellerators; STAY THE HECK AWAY FROM IT!!!!
Their software uses a funky LAN/proxy server emulation that BARELY works, and chokes your connection severely. Especially if you play web games, like MSN's Zone games.
What the advertisment doesn't tell you is the higher speed only applies to images (they get downsampled on their end and interpolated on yours) and text (it gets compressed simular to a .zip file, then decompressed on your side).
The best way to describe it is;
internet -> compressing proxy server -> LAN emulator -> diallup connection -> LAN emulator -> your internet programs
It's a great concept in theory, but, it's crap in practice. On top of all of that, the setup is junk too. They give you a downloader/dialler, and you are forced to download ~9 megs, instead of how AOL does it (they at least give you the whole setup on the disc, and allow you to download the updates seperate of internet time).
I spend roughly 15-20 hours a week working on these 'accelerated' internet services, getting them to acceptable rates (adjusting modem init strings, com port baud rates, etc). Trust me, you are FAR better off sticking with plain dialup than going with an accellerated service.
(and I didn't even get to their email client... they force you to use a rather crappy email client, instead of allowing you the choice of outlook, etc)
edit; I failed to mention that the proxy servers on their sides are down more often than not.