These crowns are incredibly luxurious vehicles. You'll feel like you're piloting a 747.
Reliability depends on how well they've been maintained by previous owners. There's a whole lot of body electricals that can be easily messed up by the wrong hands. It's built very robustly and things generally don't go wrong unless in the wrong hands.
Parts are available, but rare and charged at a significant premium.
2JZ-GE is powerful plant but slurps up fuel like crazy. With the crown weighing around 1.8 tonnes, you'll be lucky to get 12 kmph on long routes, 7-8 in the city on light foot.