It's not actually filled with critics, but anime-planet.com is sort of like imdb for anime. They generally have synopses and ratings for all series that have been out for at least a season. They also have recommendations for each show (if you like x, you might like y). The reviews and recommendations aren't perfect, and you can tell that people tend to fan[boy|girl] pretty hard sometimes, but I haven't found a better way of browsing anime (by year, rating, genre, etc...). What's also neat about it is that you can keep track of everything you've watched and want to watch (and it totals up the time for you).