Moretsu has had its declining moments that's for sure and true.
However, I am (still) watching it, if just for the two main's - however - for the story? - nah! - it drifted into space as if their ship had no power crystals to fuel it any-longer... its actually grasping..
I have noticed some slight deviation from the quality factor, as its not as it was when it started, I just wished they would add more action into it to break up the monotony.
Ah, Mouretsu Pirates. I have continued to watch it, but I openly admit that it took me a LONG time to actually get into it and even now I find it a slight bit tedious and I don't anticipate it as much as the other things I'm watching (like Jormungand, Lupin III, Acchi Kocchi or AKB0048). I don't even anticipate them as much as Nyaruko-san or Hyouka, both of which are shows which have elements I dislike but I still like quite a bit.
I think a lot of it has to do with the fact that I came in with the wrong idea of the show. I got the wrong expectation in my head, and I got disappointed as a result (something that happened to me with Ben-To). When I first read the Moetron description and saw the images of a cute girl in a stereotypical Pirate outfit and the mostly female cast members, I got the idea in my head that it would be silly, lighthearted show with some "zany antics" and some Class S friendships. I was ready for something easygoing, a show I could look forward to every week that I could kick back, relax and laugh with.
I turned out to be only right about the Class S friendship (although the show surprised me again by going beyond the Romantic 2 Girl Friendship and having actual out lesbians. Thank you Jenny and Lynn for giving us Yuri that isn't subtext)!
But besides the love between girls, I was totally wrong about the show. What I got was a very legitimate space-base Sci-Fi show, and it is far harder Sci-Fi than I was expecting, as well as being harder Sci-Fi than a good deal of Anime in general (I notice that Anime tends to softer Sci-Fi, even Real Robot tends to be pretty soft Sci-Fi). There are a lot of explanations, a lot of technobabble, a lot of world building. And not a lot of action, so there is nothing to really balance it all out.
However I must admit that I am biased against such a thing in the first place. I have always had the preference for Fantasy over Sci-Fi, and if I do watch Sci-Fi I prefer it soft, so it's less realistic and feels more like fantasy. Mouretsu Pirates is already something I wouldn't be too excited about, and the fact that I came in with the wrong expectations compounded the issue.
Also the show is VERY slow paced (as one would expect of hard Sci-Fi). The show is super dialogue heavy, and unlike say the Monogatari series or SZS, it's not very interesting dialogue to me. It's a lot of technobabble and political intrigue-type dialogue, which is stifling in large amounts. And because of the realism level that comes with harder Sci-Fi, there is very little fighting involved. There is conflict, but it's resolved with negotiations and quick wit, not laser cannons (which the Bentenmaru has) or boarding the enemy vessel. Granted, it is entertaining to see Marika's guile and quick wit as she gains it latter on in the show, but there isn't much of a balance in the show's content because of it.
The show also takes awhile to really hit it's stride, because it spent a great deal of time in the early episodes world building. Not a bad thing most definitely, but I feel that Mouretsu Pirates took too long to do it, or should have spread it out more evenly throughout the show, instead of most of it being in the beginning. It wasn't until episode 6 or so that I became genuinely interested, and even then how engaging I find the show waxes and wanes. I wasn't super interested in the finding of the Serenity ghost ship arc until near it's end, and I though the show was at it's best (so far) during the "kidnapping" of Jenny arc. The tension of that arc was very nice and I found it the most entertaining (also that arc gave us non-subtextual Yuri! YAY!!!)
Also something else (although this is a bit more subjective). I am not so fond of this show's definition of a Pirate (really they're Privateers, more on that in a second). They're job seems to be one part performance artist and one part handymen/odd job people. The odd job/handyman thing I can get, because the Pirates really are Privateers and therefore are basically government forces with more leeway in their actions. The performance art thing of "Boarding" Cruise ships and "Plundering" the goods of the ship and passengers just seems odd to me. I think they gave a reason in-universe but it still seems strange to me.
I don't think the show is objectively bad, and there are parts that entertain me, but I'm just not particularly in love with it. The hard Sci-Fi is not my cup of tea in the first place, the show is wordy with nothing to counterbalance it, how engaged the show keeps you waxes and wanes, I'm personally not really in love with any of the characters (except Chiaki and maybe Marika, but we barely see Chiaki after a certain point), and it takes a while to really "Start." But there parts where it's genuinely interesting, and there is nothing I overtly hate nor any character that really rubs me the wrong way. I'm glad I picked it up and stuck with it, but I wouldn't buy it.
To be honest I think old school fans would be more interested in a series like this as they would like the harder than what is normal for Anime Sci-Fi, the slower pacing and large amount of world building.