Podcasters Daniel and Jana Sellers had the same idea I had: there is need for a source of podcast reviews. They decided to do this in a podcast format. Every week they review three new podcasts and rate them in a scale of 5 stars. They choose full podcast series, never specific episodes, as I frequently do.
The overlap between their podcast, That Podcast Show, and my blog is minimal. Out of some 150 reviewed podcasts they have covered and over 200 I have, we both touched on less than 10 of them. Their attention goes to no field of podcasting exclusively, whereas my starting point are the educational podcasts. As a consequence, their reviews go into a much lighter variety than I do.
With their star scale and Daniel's emphasis on the technical aspects of the podcast (notably sound quality), the reviews might, on the face of it lack information , but that is not true. Maybe if you just read the blog, you might get that impression, but always, the podcast discussion contains much more information. So much more, I usually have made up my mind, before I know what rating Jana and Daniel each give.
So, check them out: site, blog, feed. See the left sidebar for a list of reviewed podcasts, ordered in section corresponding with iTunes's categories.