The M.O. of this blog being what it is (i.e. excoriating lazy-looking sequels), I submit, for your delectation, Left 4 Dead 2.
Hmm...samey. Okay, so it looks a little sharper; there are new characters (amusingly, naysayers are complaining that they look "bland", as though the cast of the first game was highly-developed); new weapons; a few new zombies; and a new setting (New Orleans? That would explain the Dixieland music). But on the whole, it appears to be exactly the same thing again.
Considering that it's only been about six months since the original came out, the question is begged: what's with the rush? The chattering denizens (God love 'em) of Webland report that this is the game Valve originally wanted to put out, but they had to release a premature version for financial reasons. Or something. Be that as it may, you'd think they'd make an effort to really switch things up for part two...this seems more like a glossy director's cut.
Of course, the gameplay in L4D was already pretty spot-on in its limited way, so perhaps there's no sense complaining; but then that leads us off into the old why make sequels at all? debate. The answer to which is "because there is no God".