Seraph made everyone look terrible once he got to go off in the fight with Mervs bouncers/security. Compared to that slow-motion fight with Neo in the 2nd flick it was night and day

I'm glad they didn't show him fight Smith because watching Smith fight like he's underwater after seeing Seraph's Kung Fu capabilities would have made it unbearable. In fact, watching the scene between him and Neo is unbearable now given how fast that cat is
I know you can spin this plot 7 ways to sunday so I have a couple points to add.
1. I think Merv is the machine world equivalent of the Mafia, and the train man is the underground railroad for smuggling illegal aliens. Obviously, their purpose as programs is more complex, but this is the human equivalent of the capacity they fill. The Key Maker was just a code key generator for getting through the super-strong encryption and accessing the restricted area The One must enter to reboot the system. Merv had many uses for a key generator so that's why he sent the Twins AKA his A-Tem to get him back.
2. I get the sense *not saying it's the case, just my postulating* that they drew on the some Arthurian tales for parts of the movie. The way Neo is taken away at the end is very much like Arthur in Excaliber., After The final terrible battle has been fought and the evil he help create*Arthur fathered Mordred, and in a sense Neo Fathers Smith by overwriting his code* which threatens everything, is destroyed by him. Albeit with help, for Arthur, it's Merlin and Excaliber. For Neo, the Oracle and the SuperJack-in the Machines provide.
3. The Scene where they are navigating the tunnel with the Squids chasing them brings to mind the Millenium Falcon navigating the Asteroid field with Tie Fighters on their back, with the gun turret work Han and Luke do in Episode4 added. The other star wars parallels that can be drawn, are Neo having "The Force" as someone noted jokingly, and the final battle having that
The Death Star is cleared to fire! vibe when the machines finally break into the city.
4. I think the little girl's significance is that she is unique. I don't think there are any other machine children. It would explain her impressive ability in manipulating the code. Afterall, her parents are both very essential and powerful programs in the machine city. The reason they need to smuggle her out is she would be deleted since she was not specifically coded for a specific purpose by the Machines, and as her father said, she would have therefore been deleted. The Oracle planned her escape and her father was doing what the Oracle told him to. Someone mentioned they thought maybe the little girl would be the new Oracle, but I think her power will be greater. She is the next stage in the evolution of her species.
5. When Neo is in the train station, just before the train comes for him, he says something to the effect of "Ok, I got myself in here, and I can get myself out" He closes his eyes and you start to see what looks like the terrain outside the machine city, then he hears the train and opens his. I believe he would have teleported to the Machine City directly had Trin, Seraph, and Morph not intervened.
Anywho, I would rate them in order of how I liked them, 1-3-2 BTW, my wife's company reserved the whole theater and sat exactly where we wanted, no lines

They paid for everything and gave us credit for the snack bar. We didn't use it all so we cashed it in and actually made $20 for going to see the movie in private screening mode :beer: