So, somewhere once there had to be someone who came up with fanservice. Probably it started pretty innocently till one day we ended up with strike witches. Similarly somewhere someday someone came up with harems... and this is the biggest and worst harem series I have ever seen.
I started watching this series as it was one of the few legal series I could watch and it was getting all kind of high grades in the review section, so I was expecting it to be a pretty fine series. Now, I could tell you all kind of stuff about the story, but the other reviews cover of all that already pretty well, so allow me to only highlight the weaknesses and strengths of this anime.
First of all, the story and characters are captivating enough to make it quite an enjoyable anime to watch. The problems comes from the fact that all the characters are forced into the biggest harem ever created which makes it impossible to develop any relations in the series at all... making the story itself quite shallow as it switches from one character to the next. In the end there are a few characters who go through some character development, but as it never causes any cross-character developments it all ends up looking incredibly shallow. Put differently, you can enjoy this anime whilst watching it and even have a good number of laughs, but the second you pause it... it's all over, whereas for a series to be good you would still feel sad at a sad part or happy at a good part.
Now the redeeming part is that the main character is strong, like so strong that no matter who he's going to battle or what kind of challenge you give him, he's going to pull it off without any serious trouble. On one hand that makes the story quite shallow as I already described, but on the other hand it also creates space for lots of light hearted comedy. In a way it makes the show a lot more enjoyable, because most shows deepen the story at the cost of enjoyment... is that worth it? Personally I do think so, because in the end that causes you to care a lot more for the characters which results in a far more enjoyable finale, but it did allow this show to hit an easy 8 for enjoyment.
All in all I wouldn't recommend this show to anybody... except if you want to mindlessly spend time without getting bored or if you're some huge kind of fan of harems... though if you have ever had a good healthy real life relationship I doubt you will enjoy the harem part which is the biggest part of the show *.
* (please please don't take insult at this, I just mean that to enjoy this you have to have some kind of shallow/different view of relationships then most people have... and the only situation i can think of where that's applicable is with people who have never had a good RL relationship, but I might be forgetting other groups as well... :S )