Lots of different opinons on that one ... Some people like the new combat features - others see it as a lot of money to spend for a game. Of course going from G3.5 to G5.0 gives you a lot more then just the new combat. You'll also see a major change in graphics and flight physics. You'll get the new water flying fields as well as some new aircraft. All of your G3.5 aircraft will also still be there ... but because of the new flight physics they will not fly the same. Especially the User created models. Most, if not all, will need some "tweaking" in the aircraft editor. All of these improvements will place a higher demand on your hardware - much more then G3.5 did.

Going from G3.5 to G5 - my advice would be to make sure that your computer will handle the new system requirements. I'd suggest downloading the G4.0 Demo. It's the only demo currently available for RealFlight and even though it doesn't have all of the "demands" that the new G5.0 has it should give you a good idea of how your system will handle the newer requirements.

Don't just accept the default settings of the demo but play with the settings to see how degraded the graphics and flight characteristics get when you place a high demand on your hardware. This will give you a more "real life" idea of what you can expect on your system.

One "saving grace" is that you'll still have your G3.5. The upgrade doesn't take away G3.5 it only adds the new G5.0. That way you'll still have G3.5 on your system and if G5.0 taxes you system too much you can still fly G3.5 until you aquire the newer hardware necassary for G5.0.

Good luck!