@Ludwig has summed it up well elsewhere. Works work well when Rovi is providing the data, and not so well the rest of the time.
This part of the system is due for an overhaul. I don’t really want to get too deep into a discussion about current deficiencies because we know it’s not working well, and we have an idea of how it’s going to get fixed. Once we have a concrete plan, we’ll start a discussion here (much like we did with the new genre features) and get into the details.