I really liked Hellworld actually. It had some cool deaths and didn't tease you with dreams or anything. So I found it as an improvement of the series since Inferno.
Inferno, IMO, was the worst one. I was disappointed with the extreme lack of Pinhead. They've been lacking him for a while, but not as much as that one.
After the first 4 movies, which sort of present a continuous story, the series takes a whole different path. From there on the movies are independent and unconnected tales with elements of hellraiser in it.
Again, as with the first 4, the quality varies greatly. And don't be fooled by Pinheads presence on the covers, the latter movies are hardly about him.
inferno isnt that bad, the fourth was eh, the one where there at the party was EHHHHH as well, and the one with lucifer in it i just didnt even get what that was about, i havent seen the one with christy cotten where she shows up again in hell after she's died, my fav hellraiser is 2, three is ok if you wanan see pinhead go all out with his powers and do some major crazy stuff, if your looking for story look elsewhere to part 2 but if your looking for action see 3, part 1 was ok alot of people liked it, but i didnt dont really know how to explain why, i just didnt like the characters of frank and julia, the comics rock if youve ever read them they show all kinda of diffrent keys, and diffrent cenobites, as well as diffrent aspects of hell
there is no need to watch 6, 7 and 8........at all.
5 (Inferno) is one of my favorites of the series. I like it better than Hellbound........they just copied it for part 6 (Hellseeker). All they did was change the characters and remake Inferno.
7 (Deader) and 8 (Hellworld) both sucked hard...........would have been better as stand alone films having nothing to do with Hellraiser as they were originally intended to be.