As a whole OOO is definetly a good series, but it is not without it flaws.
I think the higher point of OOO is Ankh, he is quite an unusual character for kamen rider, somewhat of an antihero but more of a villain than anything else. Certainly it was his relationship with hina and eiji what carried the series but it did it in a different way than any other rider series. What made ankh great for me was how he was never really a hero or a good guy, he was always the villain and i kind of expected him to become the final boss or something, the entire series he was a bad guy who had to work with the good guys because he had no choice, there was some emphasis of this in the earlier episodes and in the end it kind of payed off, the moment he regained his power he turned against eiji, but as soon as he joined the other Greeeds we saw that he was really more than a greeed, his desire was in a way greater than the desire of the others.
This brings me to another point, when i began watching OOO (i can´t believe it has already been a year) i thought the idea of the Greeeds as the bad guys was cool, on one corner we had eiji, the ultimate Bump who had no desire whatsoever, truly an altruistic person, and on the other side we had the greeeds who were literally greed, ambition and desire, the exact oposite of our main hero. At first i thought that they would play it safe and would tell a story about nobility and giving one self to others or something like that, but at the end what surprised me the most was that as we get to know the greeeds, it turns out that they weren´t really evil, aside from Maki who wanted to destroy everything, you can say that OOO´s had no villans since the greeed weren´t evil, they just wanted to live, to experiment the same joy living beings take for granted, and as we get to know eiji we realize that he himself wasn´t as "altruistic" as we once thought, he had desire but he had regrets, it is just as date-san once said, he was burned in the inside because he could not achieve his desire and that almos destroys him.
The point is that at the end we reached a common ground were OOO and the greeeds weren´t really different, they both existed for their desires just like everyone else. Just as eiji himself said, it is not wrong to have a desire, the important thing is what you do with it, and that was the final outcome of the series, ultimately the greeeds ended up being controlled by their desires, and Eiji ended up giving into his desire, but he understood that his power alone is not enough and that there is nothing wrong in taking help from others, even if you try to help. And on the middle of this we had Ankh who like the other greeeds just wanted to live, but instead of fullfiling his desire through other people, he ended up understanding what being alive was thanks to what he received from others. That´s what makes his ending so perfect, he died just like a living being, he faced his own end, and did it not because he had a change of heart, but because others had already given him what he desired, he was fullfilled, something none other greeed achieved.
Another point of interest is hina, i understand what others said about how her role in the series wasn´t really clear and i can concede to that, in many points it seemed like she had something for eiji but that never happened. The thing that helps me understand the role of hina is eiji and the way things ended, at the end eiji "learned" that it is okey to give your hand to other and to take theirs as well. That is exactly what Hina was trying to do the whole time, in a way she was just like eiji, someone who didn´t had the power to help others, but eiji gained the power of OOO and she had nothing, she only had her own power which she tried to use to help eiji, and in a way it worked, at the end Eiji took her hand and she managed to give him the help he needed. At the very least that was the role she played but it could have been better, if Eiji´s epiphany had focused more on how hina was always trying to reach out his hand for him, it would have given a better conclusion for both characters.
Now that the good stuff is out of the way let´s focus on the bad stuff yayy!!
The main problem with OOO is that it didn´t had a very good pacing, for example starting with episode 14 i think, they started to build up Tajadoru, and when it finally appeared it was great, one of the best moments in the series, but then we had 2 episodes with the Hopper yummy that kind of killed the mood we had, after that we had some build up on the mistery of ankh and just when things got interesting again, the rhythm was utterly killed with the anniversary episodes. This happened all through out the series, individually every arc was very good, ankh´s mystery, kazari as a container, uva´s schemes, the whole birth deal, they were all great stories, but the show focused in one at the time while leaving the others at the side, you watch the series in one point and you get that the greeeds are bad and kazari is even badder, fast forward 20 episodes and now it´s all about the Birth´s. If they had taken all these stories and mixed them in a better way it would have improved the series, personally i think that the characters and stories are better than what we saw in W, but W had a better story telling.
As a result of this there are things that could have been handled a lot better, for example gotou, he was a great character with great development, his slow process to become birth is one of the best parts of OOO´s, but it took too damn long, when he finally became birth the series was almost over, he is great as birth, but we didn´t get to see a lot of him, and is a shame because if you ask me, you could pretty much get rid of OOO´s and make a full series out of Birth, Gotou is that good, specially when he is with Date-san. Maybe that was Kougami´s objective.....Kamen Rider Birth!!!
Wow, this was a long post, but that pretty much sums up my feeling on OOO´s, i liked it, it´s a good series with great story and great characters, it certainly sets itself apart from other rider series since it has its very own style from begining to end, it has some pacing issues but it never gets boring, and even though the ending was a bit rushed, it worked perfectly and achieved what it wanted to achieve.
Still, Cake Boss will remain a mistery forever and ever......