RE5 is the worst mainline game in the franchise. RE6 has some fucked issues, but at the very least you aren't bored or feel lethargic while playing. Boring locales, boring characters, boring weapon selection, no new mechanics were added for mobility or aiming, forced co-op.
People that don't see why RE4 is special wouldn't be able to critically review a grocery bag. The design and pacing is what sets it apart from every third person shooter.