This games been out for a while on the PSP but it didn't come out until sort of recently on the PS3 in a remastered and bundle that also comes with Sons of Liberty and Snake Eater. It takes place I think 4 years after Snake Eater. It's a shame it only first came out on the PSP before finally making it onto the bigger console as this could definitely be one of the better MGS titles out there. If you're an MGS fan I definitely recommend picking it up.
I did like that one but I must say that is the best game series ever made IMO.
I even played back in the days Metal Gear and Metal Gear Solid Snake. Fucking great series. I LOVE THEM ALL! (to an extent) and my favorite was Guns of the patriots. Explained everything that anyone could really want to know.
Now there making Ground Zeroes which should be out next year...