I really liked Mass Effect on the basis of it's well-written dialogue (though I have had my issues with the overall plot). But, after seeing the Tali trailer (of which I was ecstatic that one of my favorite characters was returning to the game), it looks as if Bioware is trying too hard to create a much darker tone.  
 
I appreciate that the new armors in the game look like they have some bulk to it, but with the addition of the Subject Zero and Garrus 2.0 trailers, it seems as if all that Marilyn Manson from the development of Dragon Age has gotten into Bioware's heads.

Quite a few of us do think that, actually.
 
But after the Manson trailers BioWare/EA released some better, more balanced trailers, and showed they still had a good game at the core. I expect (and hope) it'll be the same with Mass Effect 2.

It's EA's marketing people trying to make it edgy. The game itself will likely have a little bit of this and that they they have shown in the trailers, but not the HXC EXTREME as EA is trying to push it as.

might i request a link to where you are watching these trailers?  
i havnt seen a tali trailer and am itching for some new mass effect  footage  :)

I do agree that Subject Zero in particular feels very paint-by-numbers bad-ass archetype #24, but overall I think the approach they're taking to the game is very exciting. Yes, it is darker, but that was their intent all along and it isn't like the original Mass Effect was a bright rainbow world to begin with; there was some real grit already.
 
As far as the Tali trailer...not sure what you're referring to other than Shepard's kinda metal looking mask when he's standing before the Flotilla Admiralty Board. Keep in mind also that the Quarians have gone through some serious shit since the first game, though if you hadn't read the second ME novel, I could see why that wouldn't be readily apparent yet.

"They've (Bioware) been coming out with such awsome stuff that I'm willing to give them the benefit of the doubt.  They haven't let me down yet. "

Dragon Age had the worst fucking trailers and marketing ever from EA, and the game turned out amazing. I would look past anything, honestly.

In terms of marketing, it's definitely EA that makes a lot of those decisions if not all. So I wouldn't blame Bioware for it, they're honestly one of the greatest developers ever.

Subject Zero is actually the most interesting character to date because of that striking contrast. And Garrus 2.0? Explain please. If you mean the return of Garrus, that seems very Mass Effect-y to me.

I think it was always intended to be darker. I mean, now the shit is really hitting the fan. Galactic governments are collapsing under the panic and strain of the Reapers, and now we've got cities overrun with mercenaries and violence. 
 
It's not as stable of a world as ME was for the first 3/4 of the story.

EA does the marketing now and they cast a wide net.  They will release video that appeals to you too, eventually.

Also: Have you seen the boxart? Does that thing scream edgy and dark to you? Although I hate this weird trend where darker means better, I would sure like it in Mass Effect. Like Empire strikes back and Indy's Temple of Doom. Every good trilogy needs a dark second chapter. But it won't end up with Shepard spouting one-liners all the time... hopefully. Nah, EA tried to market Dragon Age as some edgy piece of fantasy but the actual game didn't stray too far from your usual DnD stuff.

I trust Bioware to make another great title. Ads has never reflected their games very well.

The difference between Mass Effect 2 and Dragon Age, is that the stuff that was horrible about the Dragon Age trailer had nothing to do with the game.  With Mass Effect 2, the stuff they're showing is dialogue for the characters that they've presumably written themselves.  In which case, I am absolutely worried about this game.