But it was better. The UX was way too good, even if things like standards implementation weren't great.
I seem to recall that back then Opera stood shoulder to shoulder with Mozilla about standard correctness.
Iirc, Opera was actually quite ahead of Firefox in passing acid3, though can't remember if they were first or if WebKit was
It probably helped that Håkon Lie, who proposed/invented CSS, worked at Opera.
Until ~2010ish, Opera was per-se pretty much competitive (after that, the other vendors were implementing new specs quicker), but there were some notable differences, especially around places where specs allowed multiple behaviours and every vendor except for Opera had converged on one behaviour a decade earlier (rounding of CSS values comes to mind here, but was far from the only case), and that caused more and more problems and web-developer pain as the web became increasingly complex.
I seem to recall that the Mozilla suite had a irc client as well.
They did and still do. The SeaMonkey[0] product from Mozilla comes with all the components that Netscape^ shipped with. A browser, an email client, an IRC client and an WYSIWIG editor for HTML called Composer.