I have a similar one from Carrefour (see the thread below), and it’s fine for cooking bread, pizzas, whole chickens, etc. A slightly higher temperature would be nice sometimes, but I don’t think there’s enough insulation on these small ovens for that to be realistic. My oven thermometer says it reaches 200–210°C (depends on the outside temperature, I guess) when set to maximum and allowed to preheat.
It takes as long as it normally takes to roast a whole/half chicken – I don’t think you’d normally use higher temperatures than those above for roasting chicken anyway. You can search online for how many minutes per kilo or whatever are recommended, which will be the same here, or buy a cheap meat thermometer (I have one of those with an external probe, I think it cost less than NT$200 or something on Shopee).