Originally tried cooking frozen fish sticks and fries. It was taking too long so took out my 2 digital thermometers and found it never reaches top temp. of 450. Wife contacted Ninja, they sent a replacement, same thing. 
Tried to get service address to repair it, there isn't one. Sent another same thing. I like the oven and it cooks thoroughly and evenly, but am disappointed that it only reaches 400 after about 20 minutes. Preheat cycle is only about 1 minute so not even close to long enough.