Well, I thought this was a fun episode! I liked that Sam and Callen were like, "Dudes, we're actually Federal agents, not the mafia," and the cold war vets were like, "Whatever Mary." The individual interactions of the newly-formed partnerships were well-written and acted. I even enjoyed the cheesy final standoff, with the vets riding in to save the day (like we didn't all see that coming :)
I do agree, though, that the disastrous nature of the Old Guys' plan was kinda played down. It ended up with a massive body count, including one guy who was literally tortured to death, for basically no return. Yeah, I guess that all the dead dudes were gangbangers, but I'm not sure I buy that every one of them deserved a death sentence.
I absolutely loved the whole Kensi/Deeks and Deeks/Whiting storyline. Kensi and Deeks' scenes were so real and grounded and true to the characters and their relationship. I especially liked her "joke" that if he went to jail, she'd just have to break him out and they'd live the rest of their lives together on the lam. Because that is totally what would happen! Fan fiction writers, take note :)
As for Deeks and Whiting, I think it's a really good way both to put the whole Boyle mess to rest once and for all and to open up fun possibilities for a Deeks arc in the future. I like Whiting as a character and I think the actress is very effective (it doesn't surprise me that they have made her a recurring character, since ECO specifically mentioned in his commentary on "Internal Affairs" that he really enjoyed working with her and loved their rhythm and repartee). I loved that she kept him twisting in the wind during their whole meet-up by not admitting until the very end that she remembered his confession. Way to keep a guy off-balance.
As for the suggestion that she will keep the Boyle thing hanging over him for the rest of his career, that's an empty threat and I think he'll figure that out when he thinks it through. She can't very well close the case now, and then re-open it in a year or two and say "Oh by the way, he confessed to me two years ago. Why did I close the case then? Oh, I thought it was more useful to blackmail him with the confession then, but now I want to prosecute him with it." I think Deeks will work with her, not because she's manipulating him, but because he trusts her and because he genuinely cares about exposing corrupt cops. Oh, and please don't let Bates be a bad guy!