I had problems with my comments set-up, so people were unable to comment on the epiphany rocks article except by email: I apologize to everyone who tried. I have since fixed the comments (been away during the weekend so couldn't do it earlier), and I am including here all the comments I received by email.
Epiphany uses Gecko, but then elects to change the web font sizes and default background colours, breaking a lot of sites that expect size 10pt/96dpi and white (the former of which is actually specified somewhere in a w3c spec, I think?) - sites such as the new official GTK site, for example.
It would be nice if these 'features' could be turned off - as nice as it is for web pages to match the desktop theme (to a very small extent), it doesn't work very well in a lot (the majority?) of cases.
Also, some of Firefox's extensions are quite nice - when epiphany has a nice delicious extension (no, epilicious isn't quite enough) and the annoying jump-to-focused element bug in gtkmozembed is fixed... and maybe the re-parenting breaking pop-ups bug too... Then, maybe I'll move back to Epiphany.
Perhaps WebKit will nullify the latter two of those complaints; I live in hope :)
My take on this is: I am short-sighted and I use generally high resolution screens (120dpi). I still prefer to be able to read the text on my screen comfortably, regardless of what a web designer thinks would suit me better (and I couldn't find any reference to default font size for HTML 4.01, and I can't imagine there should be one: 10pt/96dpi is basically a size in pixels, so if some web designers want to force a font size of 13px, they should do that without pretending to be a11y friendly). And no, I don't feel like downgrading my screen dpi (I also like it to match real world sizes). As far as extensions are concerned, they are really easy to write for Epiphany, and if it was default in more distros, I am sure we'd see many more.
Also, if someone is fine with this, why not set their entire GNOME like that, and Epiphany will follow. Also, one can use a separate .gtkrc for Epiphany as well, if they want to change theme colours.
I think you should include a link to http://brainstorm.ubuntu.com/idea/229/ in your post about replacing Firefox with Ephy, so that people can vote on it.
Indeed. So everyone, here's the link above: go and make Epiphany default. :)
However, I can't use it for a large portion of my browsing because the only flash plugins that I could easily get to work in it are far from feature complete. Also, the big "pause button" thing it does when a flash item first loads is annoying.
Regardless of whether or not it technically uses the same engine, some sites render incorrectly in it. The biggest example I saw while using it semi-regularly was Lenovo's Thinkpad configuration page. The column of options would render in a too-narrow fixed-width column, whereas with all other browsers I used it in (including FF2) the column would flow to fit the window width. Clearly, the Gecko engine used in Ephy has diverged from the one used in FF2.
Do these behaviors change in newer versions? I don't know. I, like so many other people out there, don't have time to diverge from what is available in my distro.
I think the flash issues are probably something regarding proprietary software (i.e. it's not trivial to use Flash 32-bit plug-in inside 64-bit environment, but it is as possible as inside firefox, afaik). And I only know of "pause" button in two free software implementations that are indeed feature-incomplete, but are quickly "getting there": swfdec and gnash. I even prefer this kind of behaviour, but it still doesn't have anything to do Epiphany afaik: they'd work the same in Firefox.
Again, here are some problems with rendering of pages in Epiphany,
and it could only be due to font size and colours display
(oh yes, I am using a "dark" theme, and hit a lot of those). However,
these sorts of problems happen only when web designers pretend to be
designing for usability, but combine absolute and relative measures
(and 10pt is a relative measure in terms of screen pixels). It's
simple to demonstrate the same problem with font sizes in Firefox: just
+ to enlarge the font size. Or with a
theme: just set your default colours to dark background and light
foreground, and many web sites will be messed up (yes, even
ubuntu.com, which is otherwise
wonderfully designed web site).
Ok, we can admit to living in a non-perfect world where many web sites are broken usability-wise, but most of this would not affect a default Epiphany installation: default colour theme is black-on-white, and default "document" font size is 12pt, with default desktop screen resolutions being around ~100dpi (and you get to customize fonts in the same way you can for Firefox, just the starting default size is different).
But, when will those who really need better usability get it if web browsers work around some problems in web sites to make them 'look better' instead of 'behave better'? How are high contrast white-on-black themes actually working in Firefox and other browsers?