Let me first off say that I enjoyed the Full Metal Panic manga a lot when I read it however many years ago. But it seems like the sole purpose of this anime was to take a good manga and turn it in to a mediocre anime...and they succeeded.
I am not going to bother with a synopsis, A-P has one that does the job. There just isn't anything overly impressive about the story. There are 4 main "arcs" in the show, the rest of the episodes serve and mostly filler to link them together. The filler is mostly Sosuke's military antics in high school, which get old pretty fast.
The main "arcs" aren't too bad, it's just that they don't feel real. I never sensed real danger in an of it...and that's a big problem imo. If I am not actual afraid for a characters life (i.e. I know they aren't going to be killed off) it takes so much of the danger out of it, and it just isn't as engaging as it should be. Perhaps this feeling is hampered a bit by already reading the manga, but I still think it is a problem.
Perhaps my favorite of the "arcs" is the one without Kanami. Sosuke is put together with another military unit (I believe from the US) to capture a warhead in a desert country. The lack of the "save the girl" plot in this arc just made it more enjoyable to me.
Overall, there was enough in the story to keep me watching, but I don't think I ever moved toward the edge of my seat.
I am judging a 2002 anime's animation in 2012...Maybe it was more impressive 10 years ago, it comes off as average today. There were, however, some parts where they used CG which where actual kind of cool, enough to gain 1 more point in this category.
Opening and Ending were blah, but that is par of the course for me.
The sound effects served there purpose, there wasn't anything that real caught me off guard as being wrong. That said, nothing mind blowing, but a job well done here.
The voicing is another thing, however. I know this is blasphemy for a lot of anime fans, but I watched this in English. It was on netflix instant streaming (with only English), it was convenient, and sometimes it is really nice to not have to read subtitles. I think my problem with the voicing is half with the acting and half with the script. There are just some moments where the show ends up being cheesier than it should, either because poor vocal delivery or poor script translation choice. I am not going to be to hard on the voice actors here, I think overall they did a good job...but sometimes the voice just didn't fit the character (I am thinking mainly Sosuke here). Guess that is what you get most of the time with English dubs...oh well
Sosuke - Military dude
Kaname - Tsundere
Tessa - Clumsy smart chick
Enter love triangle lol. Yeah, I'm lazy, that's all I am writing for this section lol
If it wasn't obvious from everything I have written so far, I find this anime pretty average. Not bad by any means, and worth a watch if you are bored, but don't expect much. I would honestly recommend sticking to the manga.