are the newer ones (07-08) any more reliable?
The 06-08 have the Jaguar AJ-V8's which have been around for a while in Jaguar XJ's, Ford Thunderbirds, and Lincoln LS's. It was a top rated motor when it came out. Typically Land Rovers suffer from leakage- coolant, oil, etc. The first jag V8 went into the LR3 in 05 and from what I've heard the engine themselves have been reliable. Only time will tell though.
The drivetrain issues seem to have been resolved from the earlier models in the RR. They all have air suspension which basically will eventually fail- wether it be the air springs, the compressor, or valves. This can be solved with coil spring conversions which many Land Rovers end up getting. Land Rovers are always a little glitchy. The Range Rovers are especially complicated in terms of electronics. My mom has a Range Rover Sport HSE (Jaguar V8). Its been good, only real issue was a suspension fault due to bad software that had an update. Additionally it got bad gas mileage due to faulty 02 sensors. Other than that its been very good. We also have had 2 Discoveries and currently own one. They're fun to drive but not very reliable. I really think LR has however stepped up and decided to improve their quality control. They are not going to be comparable to a Honda or Toyota though haha.
The thing is I wouldn't buy a new Range Rover, ever. Well, I guess if money was no object I would but otherwise I wouldn't. They have the highest depreciation of any car. You might as well buy an 06 from a dealer with low mileage. You'll end spending 50% less and get a just as good or better warranty. If you want to buy new, go for the Range Rover Sport, they're cheaper and hold their value better. That said they don't have the refinement, beauty, or prestige of a the real Range Rover.