Despite the shitty ending, there are some good points. Doomrider is presented as a pretty badass guy, having killed four other Masters of the Hunt who'd tried to take him down (although let's be fair, previous holders of ANY Space Marine rank exist only to die like bitches for the BBEG's reputation).
[Well, given that Doomrider is a Daemon Price, he isn't finished. He's just been banished for a while, and will ride again soon. Although the specifics of a daemon prince returning when his still-alive head is being held captive are unknown ]
[Also probably not smart: bringing home the living head of a Slaaneshi Daemon Prince to hang out with your adrenaline junkie biker pals and not expecting anything to go wrong.] But at least Headrider and Headpool can get up to some 4th wall breaking dickery (because if were all honest doomrider is just a grimdark version of deadpool before deadpool with cocain).