Looking at it now it might seem the internal oven space is to small compared to others i have seen but i would say its perfect for what we want to do with it, we don't want to labour for hours setting it up, cleaning it, etc etc.
you should pick the size that will produce the results you want, eg: more size MORE WOOD ! more $$$ each time you want to use it.
this one will do 4 good sized pizzas, roasts, various breads, baguettes , "beer can chicken" etc so its just fine for our family.