"This is by far the most satisfying build of all the Lego kits I've assembled in my life time. The final model is sturdy, and feels very solid, such that you are not afraid to pick it up and move it around- no loose pieces falling off when operational. There is plenty of detailing on the excavator, from cockpit controls (barely visible), to rubber hydraulic hoses, and lots of railings, and nicely made cooling fan blades (again barely visible), doors that open to reveal the hydraulic pumps, and many other details that make this model so realistic. After reading reviews from Lego suggesting that you should NOT test the electronics until all motors and hubs are completely connected was a truism, because nothing will happen if one tries to run the tests that are suggested in the manual. And it was rather scary waiting so far into the build to see if anything worked, but everything did spring to life at the end of assembly. The cell phone control app. was also quite amazing in how many ways it gives you to control the model. The movements from all seven motors was smooth and gave realistic actions. This was in a whole new class of Legos! I can hardly wait to see what the future brings in this type of complex, remote controllable, realistic, solid, robotic devices. This was a really fun kit to assemble, and also, plenty of fun to operate. Enjoy the journey!"