I have mixed feelings on this, for one we have that the series has a theme, which is the persona of the rooftop princess. Being more than "a main character" and being the theme of the series, she should have a huge charisma, big enough to carry the whole charm of the series by herself, kinda like how Yuuko alone can make Tasogare x Otome interesting. However her charisma is just "normal" for her character stereotype (perfect, responsible, considerate, gorgeous, polite oujo-sama); the same can be said about the rest of the cast, they are simply "normal" when it comes to their character traits, they are your "run-off the mill" characters and don't specially shine in a particular, special way.
So, basically, this series has very little character appeal; thus what's more interesting is what's actually breeding between them and how things are expressed, simply, the plotline of this romance story is the one that catches more of the reader. For one side we have the princess and her feelings, she is very different from the rest of the cast because she is a more prominent entity within the story; not only because she has a bigger aura than the rest of the characters, but because she knows herself perfectly and her own character is strongly self established (well, that's only a first glance impression, there is a little more beneath her). Being a stable character we have that it's more the situation that she is in the one that is a mystery and has been unveiled slowly as the story progress and with every detail that it's unveiled about her circumstances the more that things make more sense.
The rest of the characters feel the opposite, their situation and circumstances are known to us and are pretty simple, but are their feelings, resolutions and their expressions the ones that are changing as the story progress, and how those things conflict with each other what makes the story, along with the mystery of what is the true self that the princess has locked within her heart.
The pacing of the story is also conflicted as things are portraying really slowly and softly, personally I like that since it builds up the simple "slice of life" air of the story with aid of the art and location settings, but a side effect of that is that not many things are going to happen in between a few chapters, even after reading 5 chapters in one go there is still the feeling that nothing important is being build up, that coupled with the monthly release I can understand why many just dropped this one in their early stages.
The plot is simple, albeit is very hard to foresee as many details are being kept from us, there are some twists that could happen here and there thanks to that but it's still too early to make suggestions. The character that has changed the most since the beginning of the story is the princess, however those changes had been very slight and I'm sure that she doesn't realize them. Basically this is a very soft story with good art and some mystery facts that could be unveiled further and could change everything. The story can potentially get more interesting if Tobi knows how to properly unveil what's to come next, however he seems more naturally gifted to comedy by judging from "Megane na Kanojo" and that's actually one of the problems of the story, if Tobi would have been a veteran writer by the time he started this story probably would not have any "ifs"; but has it stands now some of the evaluation problems come from character & story portrayal, and thus if he happens to gets better as an author as the manga progress, the manga is going to get better as a result. Right now is a simple story with some charm points where one has to stand for some bad characteristics to be able to enjoy. Personally I'm interested in the story's future and if Tobi can improve more and more as an author, I'll stick through his work till the bitter end.
