I voted No.
They are great, and if your buying them from the start, it makes sense to continue them. But to get them now, well individually, your looking at around £55 in UK money for the 24 copies...thats a LOT of money for what is essentially 1 single story. 1st editions make that even more (#1 1st edition wont go for anything less than £10 on ebay... on that note, I have a spare if anyone wants to buy it off me).
So because of the way your poll is phrased, I said they are not worth it. It is a good story but very different from the show imo, too much fancifulness and crazy things. Talking trees, giant dawn, super duper flying Willow where suddenly magic is no problem. I said this in another thread, they took the concept of freedom of budget and went too far with it. Buffy needs the constraint of budget because it gives it so much more believability. The comic takes Buffy and makes it so crazy, you step more into a fantasy world and less like vamps could actually exist in the dark. Buffy was always believable to me, there could be someone out there protecting us from things we dont understand...not with the comic.
There good, but in their own way.