Things I liked: The weight and feel of this gun is excellent - it fits perfectly into my hand. Though not realistic, the blowback is a nice touch and gives a nice kick. With my testing so far the accuracy is pretty average for your standard smoothbore bb handgun, and I got around 5-6 mags in before the blowback stopped working consistently.
Things I would have changed: -Integrate the CO2/valve into a full-size mag for added realism. -There's a lot of left over CO2 after the slide stops blowing back. If possible, maybe make its CO2 consumption a bit more efficient.
What others should know: -The slide really wears into the plastic around the barrel. Be sure to lubricate that area to prevent this from happening. -For the money, the CP99 is a great value