[*]The melee weapons are good when you get swarmed, but they all do the same thing, putting so many in is a gimmick.
[*]More firearms is good, no complaints there.
How is putting in more firearms (which all .. you know.. shoot bullets?) different than putting in melee weapons? It's nice not to see everyone running around with the same weapons as it adds more diversity. Not only do all the new guns and all new melee weapons handle differently, they all have different kinds of impacts. A nightstick will not do the same kinds of damage as a fire axe will, for example. It's like choosing the shotgun over the uzi.
[*]Three new SI, good. I can't really speak about them because I haven't used them yet. I've only dealt with the bullet proof zombie, which I found to be more annoying than challenging.
Again, more diversity. I can honestly say that when playing on the higher difficulty levels, Uncommon Commons are very annoying and the new SI open up a whole new way of playing and dividing the survivors. There's some very interesting comments about them in the Developer Commentary, and the thoughts behind each's playstyle. The Riot Cop can only be killed from behind, the Clown is basically a mini-Boomer as he attracts all nearby zombies because of his squeaky shoes (which by itself is awesome), the Construction Worker is immune to pipebombs because of his earmuffs, and the CEDA Agents are immune to fire because of their hazard suit. And trust me, on Expert or Realism you do not want one of these zombie bastards zerg rushing you through your own molotov. And the Wandering Witch? Jesus, try getting through the Sugar Mill with 3 of these wandering around. I've never clenched harder.
[*]More maps, that's a given. The fact that they connect with each other is irrelevant.
How is that irrelevant? I actually played through the Campaign from the first to last scenario, and it's nice to know what happens and why exactly they're getting out of the helicopter they only just escaped in. Although it adds nothing to the gameplay, it's nice to see all campaigns being connected to each other. It makes the journey much more coherent.
[*]New characters was a pointless addition. Not only are they less likable than the previous ones, (I hear the woman is getting a lot of hate, as well as the hick), but the first group had plenty of development.
How can you say they're less likable? Getting hate? The woman I would agree with, she's very bland and has very little dialogue, from what I've heard in game. The "hick", on the other hand, might very well be the best thing L4D2 added. Ellis alone has more personality than all of L4D's survivors combined. Although I love L4D1, all I know is Bill is a Vietnam veteran, Francis just hates everything, Louis is grabbin' peels, and Zoey, well.. did she ever speak? Ellis has stories that make me stop running around, just so I can hear them. They're funny as hell. Coach has a bit of the father role going on, and comforts everyone constantly. As for Nick.. Oh man. If anyone here has seen the Dawn of the Dead Remake, Nick = Steve. He's arrogant, sarcastic and a complete bastard. I love him.
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And while they don't count against the gameplay, I found the new music to be awful as well as the daylight maps.
That's personal preference, I love the daylight maps and not being in the complete dark for a change.
So what have we got in reality here that's really extra? One melee weapon, some new guns, and a few more infected types. Seems like expansion content to me.
Now how many sequels do just that?
Doom 2 added new maps, new guns, new enemies.
Doom 3 added new graphics, new maps, new guns, new enemies.
Quake 2 added new graphics, new maps, new guns, new enemies.
Quake 3 removed the story, added new graphics, new maps, new guns, player enemies.
Quake 4 added a story, added new graphics, new maps, new guns, new enemies.
See where I'm going with this? What exactly is it you want from a sequal, then? A complete change of the gameplay that was established in the original? I'm kind of lost here.