The "new" (2003 +) Range is a fantastic vehicle, in looks and in performance. The BMW 4.4 engine is miles ahead of anything LR have had previously in performance and in reliability. I had a 2000 Disco II (4.0) and there is just no comparison.
Most people comment highly on the updated NAVsystem available in the 2005 +. but many upgrade their NAV on the '03-04.
As mentioned previously there is the front driveshaft problem but there is an aftermarket fix for that. But even if you get that a continuing warranty is highly recommended, as there are little things (like Park Distance Contol) that can go wrong, and bigger things I am sure as well.
See rangerovers.net forum for lots of info.
The passenger accomodation is so luxurious compared even to the disco, and there is more passenger room. The luggage area is not as tall and because of the tailgate being at a higher position if you have a medium sized dog he will have more difficulty jumping in than into a Disco or LR3.
Sometimes I miss the seven seats in the Disco, and the roof ladder, which is not available.
I would be wary of the Range from 2006 on as it has a new Jaguar engine and although it produces a little more power its reliability is not yet established as compared with the BMW unit.
Enjoy your new ride.