I am sorry but whoever says that FF8 is a memory hog and keeps crashing,needs to check his computer for problems.I use FF and Chrome for years and i love both browsers so there is no bias in my following statement:
FF8 is by far the best version that Mozilla has released since the premiere of FF4 and the introduction of the fast update cycle.It is very stable,it is fast,it is a lot more responsive that the previous versions,the memory management is absolutely efficient and way better than the competition,the plugins always work and have never crashed and all the 60 addons which i use since FF4,are still fully compatible and functioning properly with no problems.
The only thing that FF8 still lacks compared to Chrome,is the snappiness factor which becomes more apparent when you have opened many tabs (30+ at least). Unfortunately that problem will be resolved once the Electrolysis project is completed,but until then Chrome simply excels in this department.
As far as the 64bit is concerned,i am using the FF11 x64 nightly with a bunch of addons and plugins.It is a bit faster and snappier than FF8,very stable too,it consumes more memory than FF8 does but that it is to be expected since it is an experimental release,so not that well refined.Finally it has some new features which will be introduced in the future,upcoming updates of the browser but if you are in a bit of harry,you can start using them with no problems right now.
So if you are a FF user,do upgrade to FF8,it is a very worthy update.If you are a Chrome user,do give it a try,you wont be disappointed by its abilities and features.As someone above correctly said,we need to support Firefox because without him there wont be no competition and with no competition the Internet and our web experience wont evolve.