MPO+ is a good expansion, but you shouldn't buy this game unless you have the orginal Portable Ops.
I have been a fan of the metal gear solid series, and I loved these things to pieces. They had the best story a person could ask for, if not more. Great gameplay, and awesome graphics. But do I feel the same about this one?
Lets start off with the good things. This game uses a new thing called infinity mission, where you go around completing a set amount of stages depending on what difficulty your on, endlessly recruiting soldiers, in the hope to make FOXHOUND. This is okay, and very well done, as there are alot of soldiers to get.
Another thing is there is soldiers from the other MGS's so you can walk around as a gurlukovich soldier, or Genome or whatever. There is even Raiden, Campbell and, my personal favourite, Old Snake. They claim that these characters are rare, but you unlock them all in infinity mission. Old Snake was meant to be the rarest of them all, and hes unlocked the second you do Medium.
The online has been significantly improved, as there are new maps, gameplay modes, help for beginners and best of all, you can play against MPO players, as well as MPO+ players, as long as you don't use any MPO+ characters.
Now onto the bad points of the game. There is only infinity mission, which really makes this an add on, or an expansion pack rather than an actual stand alone game. So don't buy this game unless you have the original MPO.
Also, there is a problem with the story we know and love about MGS games, and that is that there is no story. The game is basically saying "Hey you, go off and collect loads of soldiers" then it folds it arms and watches you as you do this, and he never buts in to tell you something shocking, like a main character is actually evil and wants to slit your throat.
I suppose I could do a few Nit picks, like the fact the graphics haven't changed since the last game, the entire game can be completed in a day, and that the graphics for all the new Characters are frankly shocking.
Okay, so in conclusion, MPO+ is a game which despite its flaws, you should buy it anyway, as long as you have the original MPO game, because there is no way of getting the original MPO Bosses on to you MPO+ team, unless you cheat.