I honestly don't see an incredible improvement over say Mozilla 1.6. The improvements over IE are the same for me as that of Netscape or Mozilla and thats the auto pop-up blocking. The same problems still exist though and thats 0 active x capablility. Some people may not care personally it annoys me to have to run IE for certain things but I still use Mozilla and Firefox because IE is just too hackable.
i use Mozilla 1.6, after Firebird 0.9 was giving me slight issues with stability i decided to go to the 1.5 version of mozilla.
i will wait till firefox gets to 1.0 before getting it. they changed the name and steped the version number back at the same time which indicates they don't think its ready yet.
mozilla and Firebird were alwasy the same speed, only thing i liked about firebird was the user interface being trimmer. btu witha few adjsutments in Mozilla i go them within a few pixels of each other in screen realestate.