As far as plots go, I recall offhand:
Casino Royale? Terrorist money guy plays a high stakes game that Bond needs to make sure that he loses at. Premise is frankly kind of lame. Yes, I'm aware that it goes back to an original story from Fleming. Still lame.
Quantum of Solace? American corporations in connection with international financiers are trying to steal the water resources in Latin America. Apparently based on real life trade practices. It's interesting, but... this is so NOT Bond. This is what I'd expect to see a documentary voiced by George Clooney about.
Skyfall? Bond faces Hispanic Bond. That's kind of it. And that's honestly rather brilliant. Bond having a near exact mirror image to tango with, Bond w/limits versus Bond w/o limits then... pretty alright.
Spectre? Apparently Dr. Evil is back. Blofeld, I mean. He's an evil European aristocratic dude who wants to take over the world... somehow... eh, this has been parodied to death, and everything is just... lame. There's no high concepts involved. It's Bond versus a bunch of jerks, essentially.