To recap, let's briefly jump back to the concept of the first season. Amagami SS was a story of a guy named Tachibana Junichi that got stood up by his date on Christmas Eve two years ago. In the present, Junichi is very melancholy about his love life, but is presented with many ways to get the date he was never able to get.
Basically, the story, which runs in omnibus format, is about a guy named Junichi, who technically dates six or seven girls leading up to Christmas Eve. However the story itself runs, in the best way I can describe it, as if it has parallel universes. So no, he is not dating multiple girls at the same time... technically. Specifically, the story, which is divided in to 4 episode arcs per girl, highlights the different stories that come with Junichi's relationships with each of the six girls to hopefully get the Christmas Eve date he was not able to get beforehand. To specify even more, aftereach arc ends, time resets to a time prior to the days leading up to Christmas Eve and another girl gets to be with him.
Saying all that, Amagami SS+ Plus season/show is run in the same format as the previous but in a 12 episode format - 2 episode arcs for each of the 6 girls (though it seems as if MyAnimeList is not that sure of the episode count). The story, while not necessarily kicking off right where each arc in the first ended, adds on to those stories. That said, because of the unique nature of the show, and because it is a direct sequel, going through the first season is a must to watch SS+ Plus.
Without spoiling anyone (those who have not entered the whole series series included), I'll just say that the story is nothing too major, and personally and quite frankly, with the exception of Sakurai Rihoko's arc and maybe one or two more at best that may show up in the next few weeks (the show is still airing at the moment this review is being made), the story is not anything too mindblowing - I cannot stress this enough in this review. As a whole, because of the unique composition of Amagami SS, the second season sort of suffers in that each arc is only composed of 2 episodes. This is frankly not enough to write up any major developments to add to the stories established in the first season. Actually, to put it simply, these episodes were probably made just for the fans who were literally dying to see more of the show.
Despite some of downsides I see to the show, I do enjoy it, but I don't commit to it as much as the richer experiences from other 12 episode shows. You will find some if not most of the happy and romantic qualities that the first season had. In regards to conflicts, they, again, are not as drawn out as well as in the first season, but are a decent watch to say the least. I give the show credit for what its worth.
As someone who watched the first season and liked it a decent amount, I though SS+ Plus was good at best. It did what I expected it to do - maybe it added a bit more depth to each of the characters here and there, but I honestly did not find it that necessary to watch - again, apart from one or two good arcs. That's not saying you shouldn't watch it. It's just saying don't expect too much out of it. If you enjoyed and had fun watching Amagami SS, then SS+ Plus will most definitely be a good watch as well. If you have not watched watched the first season, all I can say is that you will feel completely alienated if you watch SS+. While there is some substance for new viewers, it would probably make you think worse of the show, which is not that fair. Take note of that first season before you judge.
*Update after show's end: I can honestly say that the show overall was good. However most of my thoughts did not change over the course of the three or four weeks since the making of this review. Additionally, I'd like to add that Haruka's arc was, although predictable, a really fun and satisfying arc overall, although I'm not sure if I can agree with the show ending with Miya's mini-arc. If the show ended with Haruka, that would have been much better than dragging along the season longer than it should. If anything, this should have been a DVD/BD extra, not an extension of the season run - but I digress.
