I don't know what the specific complaints are beyond some text that didn't get corrected from earlier scans, which they said up front that they'd be using. I've still only done a quick skim through the files for mapping out content and haven't had a chance to start actually reading them yet. But at least from the digital copy perspective, I'm still largely happy with it so far.
I should note, while I grew up with the Marvel comics, I have little nostalgia for them. I acknowledge that they helped establish a lot of what's now core to the franchise, and have read the entire US run a couple times, but never really enjoyed it. I did like Furman's run better than Budiansky's, and I've always been intrigued by what I've seen of the UK stories, so the TAAO compendium specifically was appealing enough for me to go in on. At a quick glance, I haven't noticed any quality issues that look worse to me than what I otherwise have available. And I'm perfectly ok with the touch-ups that have been done, by whoever did them, given that I often hated the look of the original books.
Obviously, YMMV. I can understand someone who does have a lot of nostalgia for the originals not liking these. But as far as I can tell at this point, I've gotten what I wanted to get from them.