All around, The Second Raid has a better plot, better scripting, better character development, better action, better humor, and better animation. To get a good idea about the essence of The Second Raid, simply imagine a tighter, darker, more focused, serious, and mature series which takes all of the good and worthwhile elements from the original and improves on them. In a nutshell, this is Full Metal Panic: The Grown-Up Version.
First and foremost, what The Second Raid does remarkably well is genuinely challenge its characters, not only physically and psychologically, but also morally. Unlike much of the tactical action sequences of the first season, the sense of danger and isolation is now much more real, as well as enemies which are genuine threats and not simply a string of forgettable, one-dimensional "terrorist/bad guys" (Takima Kugayama and his "sister" from the first series) or anonymous henchmen to be easily defeated. For a more specific contrast, think of the scene from the original Full Metal Panic where Melissa Mao, armed with only a rifle, taunts and entire troop of hostiles from a rooftop, with no cover, apparently not the least bit concerned about being shot, despite the fact that half a dozen enemy arm slaves have their guns trained on her. On the other hand, simply seeing TSR's brutal and effective killing machines, the Xia twins, in action should be enough to realize that the days of relatively easy and unrealistic victories are over.
Furthermore, our heroic protagonist Souske Sagara, who was previously a fairly single-minded "military maniac" with very little sense of self-doubt, now finds himself actually having to ask the important, life-changing questions, namely, who am I? What am I doing? Is what I am doing right? and more specifically, Do I like doing nothing but following orders? Do I like being surrounded by weak people who constantly need me for support?--All questions which the first series never dares to ask. As an example, a particularly memorable and extremely well-written phone conversation occurs between Souske and the mysterious MITHRIL intelligence agent, Wraith, in which he is for the first time forced to deal with the actual consequences of his inability to adapt to civilian life--thus the series' oft-used and never-questioned "comic relief" device quickly and seamlessly turns into an opportunity for some very interesting and dramatic character development. It is also impressive the way in which the writers subtly work in a couple references to the seemingly insignificant events from Fumoffu . Later on we also get to witness firsthand what happens to Kaname when Souske is no longer there to protect her. The results are equally as enticing.
This motif applies not only to the characters, but MITHRIL as an organization itself. In TSR, we are no longer simply expected to believe that a mercenary organization which acts as some kind of a non-partisan global police force ("we fight terrorists and blow up drug factories" [sic]) can exist without its own set of serious internal problems and existential, even moral dilemmas. The most prominent instance of this is the way in which the issue of double-agents simply working for the highest bidder (i.e. mercenaries being mercenaries) is dealt with in a much more serious and significant way than the first season. TSR singlehandedly makes MITHRIL into a well-rounded, believable organization, and not simply a bunch of people with high-tech equipment on a high-tech submarine--as was implied in the original series.
Aesthetically, The Second Raid is, not surprisingly, also a significant improvement over the first series. Kyoto Animation, now known almost exclusively for their "moe" shows, demonstrate their ability to make an action series which looks just as good, if not better, than most similar shows coming out today. The CGI is surprisingly well integrated, the character designs are still faithfully adapted from Gonzo's original, and the background designs are detailed and believable (the production staff did some lengthy on-site research of downtown Hong Kong). In fact, the sheer attention to detail in general is one of the things that makes this series truly stand out on the technical level. This includes all the little things which add to the overall sense of realism, particularly in the action scenes, such as a gun jamming, someone stumbling or tripping while running, desperately padding the ground behind them for an object to throw, or even something like tiny drops of bottled Scotch hitting the table during the pouring process. On a audio-related note, ADV's dub of this series is one of the best I have heard thus far, especially in regards to rendering important conversations and lines of dialogue in a strikingly dramatic, yet believable fashion.
So while the examples are too numerous to list exhaustively, all of this hopefully can somewhat elucidate how well The Second Raid in essence works within the confines and limitations of the "Full Metal Panic universe," while at the same time managing to fully flesh out many of the interesting and underdeveloped potentialities of that universe. As a technical achievement, it is both more colorful as well as more violent, and as a writing achievement it is also much deeper and far more realistic. On the whole, this series manages to be highly engaging on both the intellectual and visceral levels, in a way that the first offering simply never fully realized. All these elements combined make Full Metal Panic: The Second Raid a personal number one favorite within the mecha-action genre.
Aside from a somewhat "rushed" finale, perhaps my only complaint about this series is its length: at a mere 13 episodes, and an intentionally "open" ending, it naturally leaves one wishing for more. However, keeping in mind that a series' length can be a curse as well as a blessing, perhaps the relatively short episode count is something to be desired if the tightly-written, plot-driven quality is sustained throughout. After all, keeping in mind that decent chunks of the first series were simply filler, perhaps a 24-episode reboot of this would not be preferable after all.
I believe this sequel is aimed at adults, not teenagers, and will have less appeal to people are faint of heart or generally unwilling to ask any serious moral and/or existential questions. Therefore for those who perhaps were, or currently are dismayed by the initial series' somewhat mediocre and "juvenile" nature, I can firmly say that the existence of The Second Raid makes it all completely worth it. Basically, this is Full Metal Panic's The Dark Knight. Only better.
