When following the link from the ars article, it actually installs two browsers; Fennec and Minefield. From what I can gather, Minefield is just the codename for the nightly builds (which tracks correctly, as it seems to be essentially a full version of Firefox). Fennec is, as previously stated, the mobile version.

-In Fennec, I seem to be having the same experience with it as most of you, crashing but blazing fast speed.
-Minefield takes ages to load (just the application), and then seems to be more stable, but not really much different in terms of speed (on simple webpages anyway). The UI itself seems to be extremely slow, but has the same set of options and such that full, desktop Firefox does.

I presume that they are both installed because Fennic requires the same backend stuff that Minefield does...

What have your experiences been with either browser?

Edit: They both work great in portrait mode too!