The weak point on a G150 is the flap/slat system. Testing it requires a special test box that most shops won't have. The G200 has a slightly better system but they didn't use it on the 150, it's the same as an Astra/G100. Pax seem to like the cabin and stand-up lav. Gulfstream has great support, it seems, no matter where you may be. Leaky flight control actuators are fairly normal even on a new aircraft, there is an allowed leak rate and prices for them are
, just like all the parts for the IAI/Gulfstream products. Try to get some kind of a warranty, they aren't cheap and will seem like a waste until the airplane has a problem. I like the 150 but prefer the 200.