To tell you the truth the way that you have to program for it in
CSS REALLY sucks. That is because there is 3 different IE systems of layout. On the other hand, Chrome, Opera and Safari all use the same layout and Firefox is ever so slightly different that you can mostly just copy-paste your code. So from a web developers perspective it really sucks to have to program for it. Also lots of people hate it because they can't get over how bad it USED to be.
From a consumer's perspective, however, the major problem with the W8 version is nobody knows how to use it. I know allot about W8 before I got it, so it was fine to use for me, but when I use a browser, I am primarily surfing with Work on the other side of my screen, and that isn't possible in W8. Now that 8.1 was come out, it is totally possible to do, but I already use Torch Browser for all my main data consumption. To tell you the truth I think I even uninstalled IE. One of the reasons I use Torch is because it is a Chromium browser. This means it has every feature of Google Chrome (another Chromium browser). It also features download buttons for all content, a free torrent down loader, a share button, and panels where you can share anything on the web by dragging and dropping. The downloads are auto-accelerated by splitting into multiple parts. It is in general very awesome.
Personally, I don't care what browser you use because as of W8.1 there is basically no speed difference that is noticeable on mid to high grade machines. Also W8.1 allows for screen splitting in a custom ratio, so that eliminates the problem I wrote of above.
Allot of people are also religiously against Bing, which I don't get because Bing is my search engine of choice. If you use it, you can even get paid (I have earned $15 no joke).
So the main problem boils down to people not generally liking Microsofts products even when they are the same or better.