I used Firefox for quite awhile, and it was fine. I just thought it was a little resource intensive. And NO, I never had any major issues (showstoppers). I never had a lot of use for plug-ins, with the major exception of Ad-Blocker and Script-Blocker -- both are what make Firefox a great browser.

I use Chrome most of the time now, and really hope the blocker add-ins come for it soon.

One main point -- why would you add Firefox as the FIRST thing??? I would seriously consider an anti-virus (on a Windows PC) as the first on my list, followed closely by an anti-adware item. -- I might even consider MS's Security Essentials as #1.

Then, worry about browsers. Its not going to kill anybody to use IE for the first 30 minutes.