Click below for my comments on the finale. Spoiler A bittersweet ending to the series to be sure (and one very reminiscent of how Gurren Lagann ended), but this was an ending that Jack earned. Aku's gone for good, Jack's back to his own time, and his homeland is at peace. Sure, it'll be tough for him without Ashi, but he's willing and able to forge ahead in her memory. I liked how all those people whom Jack had helped during his travels showed up to return the favor.
I never watched Gurren Lagann, so that ending felt a whole lot more like a slap in the face than some kind of reference. And if Aku's death means Ashi never existed, than how did she send him back in the first place? And why did it take months for her to vanish? You're not gonna tell me that they prepared a wedding and brought guests from all over the world in a matter of a few days. Yeah, I get it. Jack returning to the past means that all the people he helped in the future now only exist in his memories. It's bittersweet and crap. Emphasis on the crap. It was a hell of a ride right up to the end, and then they blew it. I haven't seen a sure thing *squee!*ed up this badly since the Super Bowl.
(You're not missing much by having never seen it, trust me.) Explaining that sort of thing involves a lot of time-travel stuff that I don't understand, and don't have the mental capacity to understand. And truthfully, I don't care; all I really care about is that Jack's journey is finally over, and he has a measure of happiness that he never had in Aku's grim future. I'm not blind to the flaws; I'm just inclined to dismiss them and move on.
I'm still pissed about the finale, but you know what? Who cares? The fact that the ending sucked doesn't detract from how good the rest of the show was. Now if you'll excuse me, I'm gonna go hang out on the part of Tumblr where Jack and Ashi got to live happily ever after.