Ghostbusters (1984)
I could understand that if you're coming at it as a younger person who's not impressed with the franchise and/or feels that it hasn't aged well. But, man-- that thing was a tonne of fun back in the day, even if it wasn't some kind of cinematic classic.
I'd argue that it was also seriously innovative, coming up with a bunch of novel tech, storytelling and plot points for that genre of movie. Lots of good acting, memorable scenes, and a truly inventive comedy adventure made for plenty of substance IMO.
Sin City (2005)
I'll agree with that one. They did a very good job literally recreating scenes from the GN, but there was a surprising flatness to the film that really brought down the interest level for me. 2D characters might work perfectly well for comics, but when you bring in real human actors, it's kind of a step backwards to play them the same way, I think.