I have had one of these for over a year now and it has been a great addition to my kitchen equipment.
It is definitely worth the money for people who are hardcore into artisanal bread baking at home. It provides the true crust that you have been striving for more effectively than the usual baking stone or tile that have been used in home ovens.
The hearthkit is VERY easy to set up - just be sure that you have measured correctly to get the right size for your oven. I recommend going to the company website to be sure how to measure and order correctly.
Be aware that the hearthkit takes a while to preheat so if you are hoping for very quick pre-heat and cooking you will be very disappointed. Using this thing requires some pre-planning. However, the results for breads, cookies and roasted meats is fantastic.
You CANNOT roast a large turkey with the hearthkit. The turkey is usually too big and you have to take the thing out. I usually roast a 17+ lb. bird so you may be successful with a smaller bird. Roasts chicken beautifully and standing rib roasts do cause envy and awe at the table.
There is a thermometer and also a rack for the hearthkit. The thermometer gives you an accurate reading of your hearthkit's temp not the oven. Think of the hearthkit as an oven within an oven. The rack is for people baking more than one tray of items.
The advantages: artisinal level of baking; great roasting; precise control of your oven environment; easy to clean and put together
Disadvantages: takes a while to pre-heat; has to be taken apart if you are roasting big items like turkey; takes alot of oven space.
It is an expensive item but if you are really into home baking this is it.