So yeah, buy MGS-PO. It’s well worth it.
I have yet to get my hands of Portable Ops, but from what I have heard its great.
There is also a Metal Gear Solid Graphic novel for the PSP, but I cant seem to find it yet.
Still, they’re both tremendously entertaining, and the stories are even crazier than Metal Gear Solid 2. They are side-stories to the ‘official’ MGS though – not to be considered canon.
I wouldn’t bother getting the MGS Graphical Novel – it’s kinda neat, but in the end it’s just the comic in ebook form. Nothing really special.
The fact that I have yet to play MGS:PO saddens me – but i’m waiting until MGS:PO+ comes out, now. So i’m kind of glad i’ve waited.