I'm giving a 4 because my first one didn't work. I had purchased a warranty so I went online and through the process and they sent me a new one immediately. I receive the new one and it works! I don't know anything about convection cooking etc so basically I found out that this does exactly what my oven does but on a smaller scale. It's nice to be able to cook things quickly without having to heat up the oven. Also I always cook with the extender ring to avoid burning and you have to turn pieces of meat and toss fries etc to get even cooking. Like I said we like it because of ease of use. I'd suggest it to anyone cooking on a time crunch. I have not tried cooking frozen items yet. I think sausage links and hamburger patties woukd be fine. Pieces of meat with bone....i probably wouldn't try frozen.