The story is basically, some mafia dudes controlled by the local pizza conglomerate murder the main character, Travis Touchdown's, buddy and leave him the guy's severed head. Travis gets pissed and wants revenge. And as it turns out, the new CEO of the pizza company that arranged the hit happens to be the Number One ranked assassin in the city of Santa Destroy, California. So Travis gets roped into ascending the ranks by killing the killers ahead of him, much like in No More Heroes 1, but in stead of starting at rank 11, he starts at 51. Unfortunately that doesn't mean 51 separate boss fights, but it's more than 10.
In the original game, you were forced to do various mini-games to earn the money needed to enter the ranking battles that made up the meat of the game and allowed you to face some of the most off-the-wall badasses in gaming. We're talking Metal Gear Solid level of absurdity here. There's a lolita-dressed drunkard of a girl that bats clones dressed in S&M gear at you as projectiles. There's an old lady with a shopping cart that transforms into a beam cannon. And there's a mechanically-powered super hero cosplayer that fires energy blasts from a laser codpiece. And that's only three from the first game.
The earning of money is no longer necessary for the ranking battles in NMH2, but is used for new clothes and beam katanas (think lightsabers). So it cuts down on the bland bits of nothing you're forced to do between the awesome parts. And the mini-games that are there have been replaced with 8-bit style games reminiscent of days long gone. Though some of the bosses are less memorable, they're mostly all challenging. If you play in Mild (medium difficulty, highest when you start. You unlock "Bitter" after beating it the first time) you will get killed several times. You cannot just rush in and bash away without care. You're forced to analyze the bosses' attack patterns and work around them, slipping in surgical hits as often as you're allowed.
The graphics are improved over the first one, but both have killer soundtracks with pieces ranging from shamelessly poppy to synth beats and hard rocking tracks.
And if you need any more convincing, the opening cut scene of the third boss (watch till 2:15):
http://www.youtube.com/watch?v=0uyI7n3Fylk
Music sample:
http://www.youtube.com/watch?v=9g8H2aCDW3E
http://www.youtube.com/watch?v=V20w1cfvmHg&feature=related
http://www.youtube.com/watch?v=w8innp-1IVA&feature=related
http://www.youtube.com/watch?v=-sON9SYIIqo
(Don't read comments, to avoid spoilers)
It's not absolutely necessary to play the first one in order to enjoy the sequel. But in order to get the most out of it, know some of the backstory, and appreciate some of the moments in NMH2 it's good to play (and a kickass game in its own right!). Not to mention the original can be had around the "Greatest Hits" classified games for $20 new. NMH2 came out on the same day as Mass Effect 2, so expect to pay full price on that one.
But seriously, if you've got a Wii, there's a million reasons to own both. and if you don't have a Wii, either is a good reason to buy one.
