I enjoy the Seneca. I’ve been flying it quite a bit over the last few months. I usually fly in good weather, so I haven’t used the radar lately. Other than the radar, there are no problems I’ve found. The fuel burning heater/defroster is not modeled, and the yaw damper switch does not operate. Those are the two main systems Carenado didn’t include. Otherwise, this is quite a good plane. Performance and fuel flow are very close to the POH. You can follow the POH checklists to fly the plane largely without any changes (aside from the fuel burning heater/defroster).
The turbocharged engines suffer from a mixture bug in MSFS which affects all turbocharged engines (the Just Flight Turbo Arrow has the same problem). Basically, the engine mixture becomes excessively rich as the airplane climbs, so leaning the mixture is required to maintain power. This should not happen with a turbocharged engine (at least, not below the critical altitude for the turbo). I wrote a little mod to correct the behavior. The thread for the mod is here: