Link sites that give personal reviews about Fansubs, here!
Whiners.Pro
This site gives pretty critical reviews of the quality of fansubs. He pays particular attention to grammar fails. He also makes note about honorifics, typesetting, and karaoke. He grades fansubs on a letter system. He's also funny.
8thSinFansubs
8th pays super duper attention to accuracy of translation. He also grades fansubs (specifically translations) on 'liberal translation,' 'difficulty' and 'overall quality' scales. Possibly important for translators who need help picking a series.