Code Geass R2 is, in essence, the most resounding travesty in the history of Japanese animation, and proof that anime fans will watch anything if it panders to them enough. It is to anime what Heroes is to US television, except that when Heroes became terrible midway through the viewers abandoned the series. This monstrosity only got more popular in the same situation. It's truly baffling.
To start, the story picks up right from R1(and by "pick up", I mean reset the whole plot), but manages to go absolutely nowhere for at least 10 episodes. The titular "rebellion" is cast aside into the domain of minor sub plots, like Ougi's relationship with that brown woman in the first season. Instead we get the genius Lelouch running around in meaningless fanservice episodes and battling characters with sorcerer's eyes. Remember how in season 1, the story revolved around interesting characters in a semi-realistic war in an alternate timeline of Earth? Ha. That much time into this season and the most important and game-changing thing you'll see is a C.C. upskirt. Then halfway through it meanders around some outlandish garbage in a plot entirely about two characters that for all intents and purposes died in the first season. Hell, the middle section of the show is so tacked on and meaningless I honestly can't comprehend why it was ever there to begin with. Finally, for the last half of the series the story turns at a 90 degree angle by the end of each and every episode. Lots of completely pointless and boring battles happen near the end, but it doesn't matter since the circumstances don't make much sense, no sane viewer has any emotion invested in the characters fighting, and the battle tactics that were once the high point of the series are now something you'd find Zapp Brannigan doing. This amazing torrent of plot holes, bad pacing and meaningless events reaches its climax in a contrived copout that probably wouldn't have even been that bad if the rest of the story were consistent. Or tolerable. Or comprehensible.
Another horrific aspect of the series is its characters. Actually, this is probably the worst part of the whole thing. The entire cast of CGR2, save for roughly four characters, is so badly written that the people on the screen can't even stick to the single sentence that defines their whole persona. Or their character is moronic. Or their main purpose is to pander to a certain sect of otaku. Or they're just boring. Or they serve no established purpose in the series at all. If someone can comment on my profile and explain why Gino, Xing Ke and Jeremiah were in this show(Crispin Freeman shouting LOYALTY is not a valid excuse for Jeremiah. Even Crispin himself doesn't know why that guy exists or is popular), that would be dandy.
Oh yeah, and no one dies in this show except for the obvious. Everyone else, be they exploded or hurled off a cliff, inexplicably lives for no reason other than to annoy the viewer.
But let's discuss the good characters in this show: Lelouch, Suzaku, Rolo. Yes, that's correct. Out of CGR2's enormous cast of about 40 recurring characters, only three are anywhere near being decent. You'd think C.C. would be on this brief listing, but she doesn't exist for half of the series and as soon as she shows up her character is completely rewritten after her only story-relevant sequence.
Code Geass R2 is Lelouch's story, first and foremost. He is the only consistent part that holds all of this garbage together. That might've been intentional, but I'm not entirely buying it. Even so, Lelouch's character is boring, his motivations change constantly and all of his "intelligence" from the first season has been relegated into performing "miracles"(cheap/contrived/ridiculous plot twists) and sending in waves of dudes to clog the enemies' cannons. His master plan and endgame strategy seemed genius enough to thousands of idiots across the internet to give him incredible praise, but it really was just as much of a joke as the rest of his iceberg summoning and floor collapsing antics. Think Watchmen, if it were written by a 12 year old.
Next we have Suzaku. The Ryuho to Lelouch's Kazuma. He doesn't exist in this story until a little ways in, and doesn't do much until halfway through. He spends a lot of his time angry over what happened at the end of last season and struggling over his tool-ish idealism. In fact, all this guy does is angst about Lelouch for a majority of the time he's around. This one time he was told to protect someone, but she wandered off and died. So Suzy blamed Lelouch, because that's how he rolls. He's basically Kira Yamato with a bipolar personality and even more immortality. Suzaku's actually a rather unlikable character and his personality swings around like a pendulum, but that's about as good as it gets in this series.
Except for Rolo. Rolo is the best thing to come out of this trainwreck. His character, despite being introduced solely as yaoi fanservice in Suzaku's absence, is the most consistent and well written in the series by a good distance. He develops, never contradicts his purpose, and was a key point in one of the most memorable and non-idiotic scenes. Ultimately Rolo was totally unimportant, almost as if the writers set him on a shelf next to the series so he didn't get covered in the sticky, smelly substance it was leaking all over the place. So sad.
The final aspect of this tripe I'm going to talk about in detail is the focus. Code Geass has none. What is Code Geass about, in the end? What is its genre? Who is it marketed to? Respectively, those answers are: Nothing, All of them, and Everyone. The only unifying thing in Code Geass is Lelouch's character, but he isn't a good character. He's not as interesting as Light Yagami in terms of personality or his goals and he's not as well written as someone like Kenzou Tenma. So really, all you have is an entire story centered around this barely-above-shounen-writing guy with no prominent driving themes, commentary or anything like that.
Code Geass also attempts, and apparently succeeded, in appealing to every kind of anime fan. The series was fairly consistent and balanced during its first season, but the follow-up did nothing but shine spotlights all over its cliches and pandering features. The character designs become more fanservicey and CLAMP-y, drawing in boys and girls. The robots suddenly evolve from bipedal tanks to laser-spamming, transforming, energy shield-bearing monstrosities. The genre fluctuates between melodrama, politics, comedy, fantasy, romance, science fiction, psychological thriller, school stories and what have you depending on the episode. It just doesn't work. Taniguchi and the writers had no interest in being original or telling a cohesive story here and instead set their eyes on making tons of cash for Sunrise.
But yeah, the animation on the DVD versions are pretty good and the soundtrack is by one of the better guys in the business. At face value, Code Geass isn't a bad series. It's mindlessly entertaining, but the issue here is that so, so many morons think it's anything more than that, which does a disservice to people who watch good, original and well crafted Japanese animation and to the industry as a whole.