Quick Review Rated 4 out of 5 stars
UPDATED 5/15/2013 - Pretty good. Cannot enable the simulator when using private browsing, however, and on one of my PCs I cannot view in landscape orientation for some reason.This review is for a previous version of the add-on (3.0).
Sorry to hear about your problems using the Simulator!
The private browsing issue is issue 246: https://github.com/mozilla/r2d2b2g/issues/246.
The orientation issue sounds like issue 535: https://github.com/mozilla/r2d2b2g/issues/535.