i've found myself increasingly going back to Firefox since FF4 was released. I still use Epiphany as my primary browser on my main laptop, but elsewhere am reaching for Firefox a lot more than I used to.
To address some of the articles points...
1. I'm not using any extensions (obviously - I haven't been using Firefox) so this isn't an issue for me.
2. For me, GMail is a lot more responsive in FF4 than it was in earlier versions. This is also true for any AJAXy sites I visit.
3. The grouping tabs feature is something I may look into if I do switch to using all Firefox, all of the time. But for now, I haven't really looked at it.
4. Firefox synch is something that I have avoided using so far. I don't have anything against it but I tend to use different devices differently, so importing all of the bookmarks from one to another is just more clutter.
5. Firefox 4 hasn't crashed on me yet.
6. The Switch To Tab feature sounds a bit messy, as described. But I'm not using it.
7. I used to suffer horrendous memory issues with Firefox 3.x - this is what led me to look for alternatives in the first place. Firefox 4 behaves much, much better on this count.
8. Ten reasons, nine reasons, what's the difference
9. I've not encountered any problems with PDF documents.
10. I have customised my toolbar - I need
the RSS button, among other things - but this was completely problem free for me.
Having gon through the writer's points, a lot of them seem to amount to: "It's different!" I'm not convinced that this is really much of an argument.