I think everyone loves that, don’t they? One of the reasons I think I ended up reading so many Iain (M) Banks books was I loved how good the covers look and liked the feel of the series.
It’s always annoying when an author either has a sudden leap in popularity or takes so long with their next book that the new book is part of a completely new selection of covers it no longer matches (obviously now I’m a Kindle wanker I don’t need to worry about this).
At school I remember reading Brian Lumley’s Necroscope from the library after seeing the amazing way the covers joined together (how the fuck this person took this photograph without lining them up is beyond me. Clearly a psychopath):
Spoiler: the first book was okay but nothing special so I never read the others.
I also liked books where the spines would look good together lined up but then I’d get slightly irked by when the position of the printing would be slightly off. 