Since there's no review yet of this, I decided I'll be the first one to do it.

Full Metal Panic! Sigma is a continuation of the original Full Metal Panic! manga. It contains different art, less comedy and has more romance to it and drama.

Story 9/10
Although the prequel contains a lot of short stories of Sousuke funnily trying to protect Midori for over all little things - this one is nothing like that. The plot gets more serious, contains more violence, and the romance between Sousuke and Midori gets deeper and more complex. It also reveals more of Sousuke's past.

Art 7/10
To be honest, when the first time I saw the art concept I was kinda disappointed. I really liked the original art - wheres you can feel more life and love from the characters. I can't really describe it, but characters design in Full Metal Panic! Sigma are not as lively and cheerful. But by the time I went on reading, I became used to it and thought, 'I guess it aint that bad~' - Although I still prefer the previous art style.

Enjoyment 9/10
I really enjoyed it. It keeps you craving for more and wanting desperately to see what will happen next. I recommend anyone who read the prequel and wants to see further relationship developments between Sousuke and Midori to read this!

Sorry if you find any grammatically error - and if find the review too stiff and not motivating... since I'm not that good of a reviewer ^^'

But I did point out the most main parts of the series~

I do hope you find this helpful - If not then I hope someone can write a better review for you to read :-)