One quote to sum up Dandan: "Whatever happens, stay in touch and help each other out" - said the guy, actually the twins' father, who didn't want them to ever meet and didn't want them to ever meet again after they found out about each other.

Story: The biggest problem of the series, in my opinion, is probably that you wouldn't know they're twins if they weren't looking exactly alike. They don't know of their existence until their 18th birthday, so everyone would probably expect them to be really close after they decide to acknowledge each other, but it's more like they're distant cousins rather than sisters, let alone identical twins. The amount of scenes they are in together is probably less than the number of episodes the show has and I couldn't really see much chemistry between them if they were together. Both of them solved their respective problems/hardships without the other and the few episodes they really relied on each other were marginal problems without impact on the story. The synopsis is also a bit misleading. The whole singing career part probably takes up 4 or 5 weeks. Most of the first half of the series, after they decided to stay in touch, is them agonizing over or denying that they want to pursue a music career. There are whole weeks when nothing at all happens and then there are weeks when everything happens all at once, without leadup or explanation. Just to give an example, in one of the last weeks of the series Megumi and the "male lead" act like they barely know each other and the next week they are suddenly married (not getting married, they already are out of the blue), without proposal or leadup at all. Sure, there was some romantic tension between them, but that was in the first half of the series, before they were even in the music business (which happens pretty much in the middle of the story).
In my opinion, most of what happens in Matsue is rather boring and the most enjoyable and interesting parts of the story all take place in Gion, even if I'm not a fan/not interested in Geiko culture and their traditions.

Acting: I can't say that I was impressed with anyone's acting. The twins, while overall pretty likeable, often looked like they saw a flying pig everytime something happened, even if it wasn't surprising at all. The accents often sounded pretty forced from almost every actor/actress and most of the characters, mainly from Matsue, were either forgettable, annoying or seemed a bit "uneducated". The best job did probably the Okami, Fujimura Shiho and the Geikos, especially Kyono Kotomi and Kimura Fumino, even if their roles were very small. The worst performance was definitely by Yamaguchi Shoko, who plays the "male lead", the music producer Ishibashi. It was like everytime someone needed to push an on button if his part came up. Very robotic throughout the series and he always sounded like he was reading all his lines rather than just saying them. He was also giving me the impression that he's always one step away from luring them into the porn industry. His character seemed like one of those super shady scouts on the streets of Harajuku who are trying to trick girls into debt which they then need to pay back by selling their bodies.

Music: They were or at least wanted to be singers, but it's only 2 or 3 songs they always sing/play. It gets pretty repetitive. Not that they aren't good singers or the songs are bad, but they could've explored the music part a bit more.

I liked some of the side stories and the character development of the twins, but that's probably the only reason why I actually finished the series. I'd only recommend it to people who are really into the Geiko and Gion culture and traditions because that was the best fleshed out part of the story.