I'm a former Land Rover owner, although I had a Discovery Series II as opposed to one of the current LR3/LR4 models.
Land Rovers are fantastic vehicles off-road. The owner community is great, especially if you are into the off-road/modification angle of it. Depending on the area of the world you live in, owner meet-ups and excursions are common, although I would say these tend to be older vehicles.
Lots of electronics and they break frequently. I had to deal with numerous water leaks on my Disco, but have not heard complaints about that on the LR3. If you are handy and into DIY, it's a good way to bond with your vehicle and fellow off-roaders. The dealer network is hit or miss -- I was disappointed with the dealers in my area. Short of DIY or a trusted local mechanic, dealer labor and part costs are very high.
Spend some time on discoweb.org browsing the forums. Also, Rovers North and Atlantic British are good parts suppliers.
I loved my Land Rover, but would not make it my only vehicle.