Too few details IMHO. Like: how many pax you plan carry, what runways and how long are the average legs...
Learjet 60 is a robust and comfortable airplane. Don't know why would you think other way.
It has APU. Not so super reliable but, if maintained by a person who has seen more than one of that type, works well. Same thing regarding the airplane itself. If pilots do not brake it by impelementing their "own" versions of checklists and use it properly, then almost only scheduled maintenace.
Depending on how many hours you plan to fly, but if 300-500/year this is a very good price-to-value airplane.
Runway... Well you can use it at 3900-4000 ft runways if not under AOC. That would be the only weak point I see.