This was my first "big" set, I must have been about 4 or 5 at the time, and I loved it!! Apart from generally providing a large number of good bricks, this set was great because:

1) You got lots of wheels, windscreens and headlight panels to make lots of cool cars.
2) The turntable. Could be used to make everthing from articulated lorries to helicopters.
3) The hinge!! Brilliant for lorry tailgates, spaceship doors, gun platforms etc etc.

You also got windows and stuff to be able to build houses, which was cool.

So not only was this a great set with a big baseplate to play with, it also gave you the foundation for literally hundereds of other models you could build yourself.

Sadly the baseplate finally gave up the ghost and split, and my kids recently broke the hinge, but the rest is still going strong to this day!!