Mercenaries 2: World of Flames [PS3/360/PC/PS2] is a must for everyone that likes FPS:es, GTA:s, war games, free-roaming games or racing games. I also recomend the older version Mercenaries: Playground of Destruction [XB/PC/PS2] which actually is the best last-gen game I've ever played!
Mercenaries is not a "ripoff" of GTA. There are similarities between the two games, however. You can hijack vehicles in Mercenaries much like you do in GTA. You also can roam the area you are in freely, like you can roam the cities in the GTA games freely. That however, is pretty much where the similarites end. The only other comparable aspect is that there are missions you can take on in Mercenaries, but those usually differ dramatically from the missions in the Grand Theft Auto games.
Here's my opinion of the first Mercenaries game (XB version):
It's a game with "never-ending action". New enemies will always appear somewhere in the city, and there's always something to do. You can basicly blow up everything, every building and vehicle etc., and if you manage to hijack a helicopter with a winch, then you can grab things you never thought you could, even fences! There are odd-job challenges to do, bounties to find, "Deck of 52" to verify, faction missions to do; it's so much of it so you'll never get bored! Even when you do "everything you should" there'll still be things to do, like "C4 Fun" (blow up a vehicle in air) etc. The graphics are extremly good for being an old-gen game. Definitly a must!
Here's a question from a FAQ:
Q: Should I get this game?
A: That is without a doubt, THE most asked question thusfar. In my
opinion, Mercenaries is a must buy. But I don't know your specific
tastes in games, so here are a few things that if they apply to you,
you should get this game:
1) If you enjoy a free-roaming experience with the ability to do just
about whatever you want to whoever or whatever you want however you
want.
2) If you want a game which has so much to do, you won't ever get bored.
3) If you like any sort of military combat game.
4) If you like GOOD GAMES!
Mercenaries 2 isn't released yet, but I'll surely get it! If you can find the PS2 or XB version of Mercenaries 1 (released 2005) and you've a BC PS3 or 360, then you really should buy it! Mercenaries 1 is now almost 3 years old, so it will be cheap to get, and it doesn't look worse than any current-gen games (at least the XB version). If you don't have a PS3 or a 360 yet, and just have a PS2, then I recomend to WAIT for the next-gen version of the game, because the graphic differences between these platforms are huge!
Here's the order I recomend you to get these games for (mostly because of better graphics and shorter loading times if any):
Mercenaries 2: World of Flames [PS3 -> 360 -> PC -> PS2]
Mercenaries: Playground of Destruction [XB -> PC -> PS2]
HOWEVER, THIS IS NOT A PS3 EXCLUSIVE, BUT THE GRAPHICS MAY BE THE BEST ON THIS PLATFORM!
By the way, everyone that got this game loved it! Really!