Faults:
Carburetors will be tricky on an old machine like this. Needs adjustment as other parts will inevitably fail due to wear and tear. Need to be mechanically savvy, as to adjust the carburetors alone can be an easy $300-400 at a mechanic; that's not considering if there are other problems that need to be fixed first.
Head light is weak and doesn't do much at night.
The exhaust is pointed on the slight angle, pointing directly under the storage bags (on the XJ700), causing your hands be always dirty if you touch it.
Pretty weak brakes and stopping power if compared to modern machines.
Doesn't like the traffic as it's an air cooled North American Model. Heat will be felt if standing for a long time.
Most annoying is that fuel tank is only 13L and other fuel tanks from SECA do not fit. With a passenger or luggage, expect 8-9L per 100 km. Range with this tiny tank is only 122 km without hitting the 3L reserve; not too good for long trips.
General Comments:
Comfortable for both the driver and passenger. Softer suspension with long travel on the front forks, having more give when braking hard.
Cheap and widely available tire sizes. Very very quick bike for an 80s machine, still giving chase to the modern beasts. Lower insurance (Canada) as it's based on the value not on VRGs. Shaft drive - hassle free maintenance. Looks better in person than on the picture. Feels great to ride, very comfy position.
Nothing can beat this bike at this price. One can be picked up under $2k. Some under $1k, but expect that YouTube electricians already messed with all the wires on the bike. To tune the carbs you will need a special tool to block all the carbs (depending on the year, but most XJ).
A positive is that I'm not afraid to scratch it, drop it or try out things I'm scared to on the other more expensive bikes