I’m not a fan of them overmuch. The 90s were filled with gimmicks: covers that were card stock (it was novel then), die cut, glow in the dark, scratch and sniff… That was just the covers. The books themselves: the so-called grim and gritty books, bad girls, and more. And don’t think that Marvel and DC were above the fray. While they weren’t as bad as some companies, they also put out some books that tried to capitalize on the new craze. (This was also part of the speculation bubble that drove sales for a while, causing there to be a lot of flash but no real substance. Marvel even went so far as to have a campaign stating they were putting the character back in their books.)
Gimmicks have their place, but I believe they should be part of the story and not just a way to prime the sales pump.
I read a script once where the gimmick was that the series could be read front to back and back to front and still make sense—it would still be able to tell a story the reader would be able to follow. I thought the idea was brilliant. That was a gimmick that would be worth pursuing. (The execution was abysmal, if you’re wondering. The idea was sound, but the writer wasn’t able to effectively tell the story.)
I would love to see a comic that followed the film Clue with its gimmick: a book that has different endings, and then a collected edition that had all the endings for those who missed the other ones. To me, that’s a gimmick worthy of the name. (And the reader wouldn’t know which one they had. No different covers for which ending was inside the book. The only different cover would be for the book that had all the different endings, as well as being sold at a different price point.)
There are a lot of gimmicks out there. Just vote with your dollars to buy the ones that are truly worthy of the name.