Speaking as someone who was given an xbox and a copy of ME1 in April, and who has only just finished ME3 (it's been quite a while before this that I was any kind of gamer) .... I really have to reluctantly agree.
I've trotted over to the IT threads and, well, as much as I'd like to believe BW still has something up its sleeve that will make everything OK ... well, put it this way. The argument is either that
A) IT or something like it was planned all along, or
There was just a whole lot of bad writing involved.
The real problem with
A) is that even if this interpretation is correct, well, they've actually written
that badly. And handled it worse. So you really
do have to assume

.
And, like the OP I also find rather strange this suggestion that the writing was just great right up till the last 10 minutes or so. I mean
A) they had well and truly written themselves into this hole by the last 10 minutes anyway (IT doesn't
fix the ending, it offers a means to have a second go at it) and

How can one simply ignore the glaring pieces of stupid that had appeared by this point?
Like how the Asari apparently based much of their society and technology on millennia-long study of a working Prothean beacon - which included not just any VI, but the very one over-seeing the
crucible project from last cycle, who could detect indoctrination no less - yet they were just as clueless as the rest of us about reapers/cycles. And the whole forced ill-defined super-weapon we suddenly found complete blueprints for at the last minute in the ruins of a civilization so sketchy we apparently knew almost nothing about them at all before now, when we pretty much seem to know everything.
And, as I've said, even assuming something like IT, they still have to write themselves out of a few holes in a manner actually thematically consistent with the rest of the series. Like:
1) What in the hell is the reapers motivation, even in general terms? These beings have been presented to us up until now (well, in the first 2 games, at least) as, like, space cthulus/gods with minds of their own. What
possible motivation could be so compelling as to see them, without any apparent internal
dissent even, limiting themselves to this strange existence of hibernation interspersed with war and slaughter. I mean... none of them even seem to get a little bored with it, let alone take a philosophical objection. The dark energy thing
possibly could have/could do a reasonable job of this, as could simple reproductive necessity or something like it (though I think it'd be quite a stretch), but the synthetics vs organics thing is patently ridiculous, at least as it has been presented to us. A 'they just like it' explanation is much better than
that.
2) The human reaper in ME2. What was the point of that? What, exactly does Harbinger mean when he says "we'll find another way" to the collector general? The Arrival DLC made clear that the collectors efforts certainly weren't needed for the reapers to reach the galaxy, or even to expedite their return meaningfully at all (they were actually expecting to arrive well before its completion). In fact, if anything, it looks to me like the human reaper construction was a rather pointless tactical error on their part. Or a diversion for them to pass the time while they made their way to the galaxy (don't you just hate long trips?) Was the second act really just killing time while we waited for the third? Really?
3) Most importantly, the major logistical problem of actually, you know, beating the reapers. Or even just
surviving through the cycle. The reapers have almost literally been set up as the irresistible force here, who have managed to pull this off thousands of times before. It's actually fair to say that the only force they even intimate at before the third act that could plausibly stand against them is, well, them. This is a pretty major hole you've got to write your way out of.
I think a skilled enough writer could probably do a decent job of writing their way out of there given the whole of ME3 to work with, but it's pretty damn hard to just change the last 10 minutes and manage it.