How much didi you pay for Legendary? I paid $2.50, A very fair price for this game...
I understand why people give this game such low ratings, it started as a full priced game and it ended as a below standards FPS.
It's not a bad game at all, let's start with the visuals, it's powered by the Unreal Technology, it looks fair, and has some performance issues, but it's not an unplayable crap as other games like Shadow Harvest: Phantom Ops (Wich i bought too at steam's autumn sale).
Characters look a little ugly, but the enemies are very detailed.
Ok, let's go to the gameplay... It's a generic FPS, all you do is killing monsters, soldiers, turn valves on, push buttons, etc. But it manages to create an atmosphere of chaos that looks pretty good.
Weapons are not very varied, you know, Handgun, shotgun, SMG, Assault Rifle, LMG, Rocket Launcher and Flame Thrower, they work fine and are fun to shoot, but there's nothing special about them.
The enemies have a decent AI, specially the human foes, monsters come in different sizes and shapes, all of them tough and fun to shoot at, you get to fight giant bosses and that's good.
Is legendary really a 3.5 rating game? Well it depends on how much you paid for it, if paid full price, yes, you can feel angry, but if you are in a budget looking for a nice simple shooter for your weekend, pick it up, you'll have a nice time with it's 5 hour campaign.
I didn't rey the MP, Why would i care about it if i already own Battlefield 3?