I'll kick-off with:

'Transformers - Age of Extinction'. The critical reviews have ALL been so damningly negative, I just had to watch it. :)

What a waste of 165 minutes of my life. :( Nothing redeeming about it at all. Cr@p script, cr@p story, loud, confusing, loud, mindless action and did I mention LOUD?!!

Special effects sci-fi/Superhero blockbusters can be done really well (Avengers Assemble, Xmen First Class, Batman, etc). Michael Bay needs to take some lessons from these.