Excellent synopsis.
Big Swirly Sky Thingie. Pointless MacGuffin to move the pace along. CGI Army for the Avengers (or whoever) to fight. Buncha snappy comebacks and one-liners.
That being said, there are a few highlights. The original Iron Man was pretty good, as was the first Captain America. The two Cap sequels were OK.
I've missed most of the ones over the past 2-3 years, WBill Jr just dragged me to "Avengers III, The Quest for More Money". I'm trying hard to miss "IV, We Need To Pay Robert Downey Jr.'s Salary Somehow".