Well, I'm still excited for it. I've done my share of bitching, but that's because most of the current ME related threads are ***** fests. And I have had my faith in the ME series shakened a bit, as I found two, in retrospect, to be somewhat of a disappointment, though a really good game in its own right.
It just didn't match the first one for me, or my expectations for what a sequel would be like. I'm still getting the third one, and though I don't expect it to be better than the first one either, if it's as good as or better than the second, I'll be satisfied.
And, yeah I'll admit I was at first reluctant to have multiplayer, but it's completely optional. The main reason I didn't want ME3 to have it was because it just furthers the idea that every single game must have multiplayer, something I really don't believe. But yeah, the execution looks pretty good, and though it's not my thing I can easily see it being other people's thing.
And, as for the switchable game modes, I personally think it's mostly a good thing. It allows people to get what they want out of the game, that being said I still do think it's a bit silly to try to hook people into your trilogy in the third installment. But it makes sense from a prospective business point.
Those are my two biggest gripes and they don't even bother me all that much, and whenever I complain about them you can be sure that's it's usually overplayed.
Those are my personal thoughts on the matter.