Mouretsu Pirates is effectively a slice of life show jammed into a space opera. Because of this, it feels in many places that the series is not entire sure in which direction it wants to go. This is amplified by the fact that the series takes the plots from several of the light novels without trying to tie them together. The result is a series of unrelated story arcs that begin out of nowhere.
Mind you, the story arcs themselves range from incomprehensible to interesting. In some cases, the conflict is resolved without fully explaining how the conclusion actually ties up the loose ends. In other cases, though, everything is brought to a close while still making sense. The good stories keep my score in this category up, but the disjointedness of the series as a whole winds up removing quite a few points.
What can I say about the art? There are plenty of very pretty visuals, from the shots of Marika's Elaborate University High to all the little things like the omnipresent computer displays that float in the air wherever they might be summoned. I am not a fan of conspicuous CGI in anime, with the contrast between traditional cell shading and 3D action always feeling jarring to me. I recognize that it is sometimes necessary in this day and age, but I don't have to like it, forcing me to take a point off.
Not being an audiophile, I can't give an informed opinion about this aspect. However I do want to point out one thing that bugged me throughout the show: Why does the captain's quarters creak like an old-timey wooden ship?
The bridge crew of the Bentenmaru are all unique, each with their own quirks and all with very nice character designs that set them apart from each other. The mystery of whether Luca really has mystical precognitive powers or if she's just making things up as she goes along was fun the whole way through. And the reveal of why Kane's character often seems bipolar was quite delicious. But, for the most part, you hardly get to know anything about them. Why is Schnitzer a cyborg? How and why did they originally join the crew? And who the heck are all the guys you see sitting in the halls every now and then who supposedly run the ship?
As for the Yacht Club, the best one can say about them is that... well... they exist. There are a couple that come to the forefront eventually, such as Jenny, Lynn, and Ai. But, for the most part, they're just a gaggle of high school girls in the background who are there to go "Squeeeee!" when something interesting happens. They all supposedly have backstories and a number of useful skills (or so we're told by Misa) but we rarely get to see that in action.
Also, as a nitpick (and hopefully avoiding spoilers), I'd like to mention the end of Ai's character arc. Basically, at the end of it, she finally loses her protective puppydog hat, signifying major growth, on her part. However, in the next scene, she has her hat again, making it feel like all of the development was completely undone since then. It's almost like they preferred to ignore who she became, all for the sake of maintaining the original character design.
Mouretsu Pirates is an okay show. You do get pumped up when the opening starts playing and it's possible to ride that high for a little while. But, eventually, you either enjoy the events that are unfolding or you don't. The important thing is that you want to stick around long enough to find out whether you'll like it or not. Sometimes, you get bored out of your skull. Other times, you're hooked from beginning to end. That inconsistency can easily threaten your enjoyment of the show.
As mentioned above, it's an okay show. It is most definitely not some piece of generic schlock that you usually see littering the anime world. It instead has a great space opera setting with a fun story concept. Unfortunately, Mouretsu Pirates is lacking in execution. Marika, the central character, is not quite enough to link the whole series together. There needs to be a lot more to make it feel like a single story. And much of the world is either thrown in at the last moment or kind of glossed over with the hope that nobody will notice.
Having never read the original light novels, I can't say whether the problems with the individual plots were due to the adaptation or whether they existed from the very beginning. There are so many things that either didn't make sense or weren't given a sufficient explanation. The bits that worked did so very well, being interesting or at the least amusing. But the bits that didn't work... really didn't work.
So, in conclusion, Mouretsu Pirates is a nice little series that is great to watch once. Though I would not recommend going out and actually buying it.