That's what makes "Carnival" so great: it's very ironical. "TYPE MOON" managed to recognize and make laugh out of various minor flows in their projects("Tsukihime" and "Fate/SN" respectively). It's captivating to see, how two franchizes that sometimes raise important quiestions,(such as the meaning of justice or the process of falling into madness) got combined in such a silly way, making it even more fun.
"Carnival Phantasm" is definetely a fan service product. However, instead of creating a typical OVA or ONA, in which characters go to hot springs or a beach(though there is such an episode in these series), people in "TYPE MOON" decided to concentrate on humiliating these two universes and characters. That's what I find the most fascinating.
