Naruto where people die... Alot.
I'm the kind of person who enjoys anime with depth, character development, and powerful themes. None of these are present in Basilisk, but because I dove into it knowing what it was as opposed to hoping for some masterpiece, I was able to relax and enjoy nearly every episode. There is something morbidly exciting about a bunch of super powered characters being introduced, wondering how they'll kill or be killed and not worrying about character development. As a matter of fact, the funny thing is that basilisks biggest weakness is trying to develop characters as opposed to just focusing on the action.
This is because due to the nature of the show, the characters were inevitably going to be weak, so giving them attention just draws attention to that weakness making it more glaring.
The tone could have also been darker, and some characters could have looked a little less goofy.
The only two episodes I truly didn't like was the worthless halfway recap episode(who ever though these were a good idea?) and an almost purely flashback episode later on.
On the plus side the animation is pretty good(though the fights seems to get less flashy as the series progresses) and the character designs distinct(although some characters are put together with minimal integrity and clearly "throwaway characters"). The soundtrack is also surprisingly great.
However, my absolute favorite thing about Basilisk is that you know (pretty) much any character can get killed off at any time, sometimes even the episode they are introduced. This in conjunction with not knowing some characters abilities can create very interesting situations, and because there are almost no characters portrayed as "good guys" the outcomes are almost always satisfying.
My best comparisons are:
A Naruto where people actually die(remember when chouji "died" yeah he'd be dead for real in this)
And Ninja Scroll, though it is two teams fighting instead of one man who will obviously succeed against each foe.
Overall Basilisk is exactly what you expect, a fun and violent diversion where a lot of people die.