I love this car. Having owned a few other Javelins and AMX's, I had a good idea what was getting into when I bought the car, even though it wasn't running then.
After a days work, I got the Javelin on the road. I get more second and third looks driving this car than any ten Corvette drivers do. If I hit a red light, it's about a 50% chance the person next to me will roll down their window and try to strike up a conversation about the car. Almost every time I stop and fill up the tank, I get sidelined by curious people.
The cockpits of the 71-74 Javelins are my favorite place to be when behind the wheel of a car. The layout is biased toward the driver, everything is easily accessible, and it's built on a scale that fits a tall 6'3" guy like me, without compromising my comfort or making me look through the tint strip at the top of the windshield.
The back seat however is more of a shelf than a seat. Like Camaros and Firebirds, the rear seat is vestigial like the tail bone of a human, a throwback to an earlier time when they served an actual function. This isn't a bad thing, just don't try sticking a friend in the back seat and expect them to still be your friend at the other end of the ride.
These cars are great representatives of the pony/muscle car era, and you will never have one just like yours pull up next to you at a stoplight.
An issue to be aware of if you live in a city with notoriously narrow parking spots (like San Diego) is the length of the doors. I have an ace in the hole in that regard, being disabled, but when the disabled spots are full, it can be tough to find a spot to park the car in that still allows me room to get out.
Buying an AMC gains you membership into a tight knit group of enthusiasts, who will be more than willing to bring you into the fold and help you realize your vision for the car... as long as it doesn't involve installing a non-AMC motor.