The basic story is crafted for baby-boomers who are reaching retirement age who feel that they are being kicked out by the young whipper-snappers, while they still feel strong enough to throw a few punches. It's a classic plot. In a way, it's Big Jake. But you know what? It still works. Especially when you have witty, pithy dialogue. And no one does wise cracking everyman better than Bruce Willis. Even when "everyman" is a retired CIA black-ops officer.
Maybe it's just that I've been in love with Bruce Willis since he stared in Moonlighting in the 80s. It's true, but I have actually seen him in things that I didn't like.
But I like all the other people too. The professional women were strong and confident. They were greatly respected by their male co-workers. The men were competent yet still caring. The characters are great. The plot pacing was great. The images were great. I mean what could be more striking than Helen Mirren in an evening gown and red lipstick firing a machine gun?
ETA: I found it interesting (and great) that "Bruce Willis has revealed that he threatened to walk out of latest film, RED, if producers cut 'sexy' scenes of Dame Helen Mirren with a gun," according to the Daily Mail. I'm appalled that he felt that he had to take that stand. You may or may not like this genre of film, but if you're going to have it, keeping Helen out of the fun seems agist, sexist, or both.
* I define a "Bruckheimer Special" as an action/adventure movie that is high on explosives and has characters heavy with snappy dialogue. It's forumlaic, but it's a formula that works. They include Beverly Hills Cop, Armageddon, and Pirates of the Caribbean just to name a few. (Actually, I checked out his resume over at IMDb, and I'm amazed at all how many of my favorite films Bruckheimer's been involved with.)