This was bought for my little boy who loves all things lego, he has a few bits of ninjago but this was mainly purchased because it was a bike!
It is a bit fiddly to put together so from the age of 6 upwards is a good guide.
It measures approx 27 cm long and is made of 156 pieces. You get the blue ninja with it, Jay I think he's called and a skeleton baddie with a helmet on. They both come with weapons to batter each other with.
The bike is a cool design but does fall over a lot due to having only 2 wheels(maybe a trike would be easier),it has a feature where flicking a lever causes a bit of the bike to spring forward supposedly squashing anyone in front of the bike. This sort of works but usually makes the bike fall over as well.
Overall a great looking model and two interesting figures to play with.
Hope this helps