Crisis on Infinite Earths
So, we have cross overs from Titans, Arrow, Supergirl, Black Lightning, The Flash, Legends of Tomorrow, Batwoman, Superman Returns, Batman The Animated Series, Adam West Batman, etc etc etc
As such, there is a lot of great fan service. Having Kevin Conroy play old Bruce Wayne was awesome. Brandon Routh reprising Superman from Superman Returns, while continuing to play Ray Palmer, and that getting addressed was amazing, as well. I am among the supposed minority whom enjoyed Superman Returns, so yeah.
I stopped watching Arrow, Legends, and Flash several seasons ago. Batwoman and Titans I have stayed current on. Black Lightning and Supergirl I may have seen an episode of at some point, perhaps a previous Supergirl/Arrowverse crossover. For Crisis, I went ahead and watched most of the relevant episodes in each separate show, forgoing the majority of Road to Crisis, as it wasn't sufficiently engaging for me to get engrossed in it.
Once we get to Crisis, it is enjoyable enough. I enjoyed all the tie ins, and how things were handled. The Black Lightning Episode is probably one of my favorite in the whole event.
Some of the practical effects, and cgi are pretty crappy, which is pretty par for the course with these DC titles. A couple of the fights involving the Kryptonians, I feel were a bit underwhelming considering the cousins abilities.
If you like DC, Watch it. If you enjoy this level of juggling in shows, watch it. If you enjoy a few specific aspects, you can largely be selective with episodes and not miss out on too much exposition.
Overall, it's what one has come to expect from WB/DC.
With that in mind, I'd give it as a story arch 4/5
When compared to TV shows as a whole, 2.5-3/5 (as with most of the DC live action shows, due to production quality, story writing, acting)