The company that originally designed them had a good product. It works. I have one and it flies well. I also have a cheap knock off one and it barely flies. The cheap knock off is close enough that it is hard to tell them apart. The main visual differences I could see were the knock off has a 3.6V Li-Ion battery and the real one had a 3.7V one, and the cheap one had a thicker PCB. The IR transmission chip used is also different with the cheap only allowing 2 channels rather than the three of the original. Note, the helicopter is fixed in frequency, and then you select one of two or three channels on the transmitter to match.
They are indoor use only except on windless days. The air currents from forced air heating or ceiling fans blow them all over the place and make controlling them hard. The controls are a simple up/down, left/right, and forward/back. They also have a trim to control unwanted spin via changing the speeds of the counter rotating main blades. Forward and back is via a small vertical rotor at the tail. It pushes the back up or down and thus controls forward and back motion. They can't go sideways like a regular helicopter control system allows. I find them frustrating as I am used to a regular helicopter cyclic/collective pitch control system. Recharging the battery is by cable from a 5V source like a USB port. Another thing is if you are going to hit something, shut down the main rotors, and much damage to the rotors will be avoided.