The art is good, the fan service is great, the voice acting and sound is great. But.... to be honest... if you don't follow the manga... well... I wouldn't recommend this. While each chapter for the manga was short, it did have a nicely paced development, but this one just takes a few moments of the manga and animates them. As a person who read the manga, this worked great, but it didn't feel great as a stand alone anime. As a reader of the manga, this added feel for the manga and helped me enjoy the series as a whole more. But it doesn't feel like an anime seriesrather than an OVA series for fans of the manga.
Of course, if you like fan service and that is enough for you, then go ahead and watch this. You'd enjoy it.
The characters aren't unlikable, but they don't feel fleshed out if you take this series on its own.