I would definitely trust reviews over sales.
For example, Super Mario Brothers Wii has HUGE sales, and I think I've played it 2 or 4 times – it’s just too frustrating and I don’t like the controller. While Endless Ocean 2: Blue World has much smaller sales, but I like it much better and play it more. (I do realize they are different styled games - Wii Play has HUGE sales.)
Also, another thing I have noticed, is that the really good games hold their value better as used games. Super Mario Galaxy used, was until very recently, nearly the same price as new.
Better yet is to try a demo.







