These are both gentle satire - but completely hilarious - series on the BL genre. There is a lot of observational internal-dialog which drives a less-subtle humor so they are easy to watch mindlessly. Also, the eye candy is delicious!
Both are entertaining battle parodies - one of the historical warlord era and one of the modern-day host clubs. But really, you're watching because they have large casts of beautiful guys looking super-cool. And it's worth it.
If you enjoy watching Yutaka's expressive face- which is to say Inukai Atsuhiro's wonderful acting - the Zettai BL specials are all must-watch! His beautiful face transforms to reflect all the different aspects of obliviousness, confusion and ultimately acceptance. The tone of the two series are very different but both have a warm, gentle center and make you fall in love with Inukai.