Best :
Building.
Painting.
Bringing an old heap off ebay back to life.
The endless research for the next build / hop up / spare / idea / bargain.
Worst :
Cutting and sanding lexan.
The prices total wrecks are making on ebay right now.
Finding a good spot to use your cars.
Youtube videos with overpowered cars cartwheeling all over the place. Leave that to the Traxxas / Arrma brigade