Yes. urxvt is pretty minimal and will likely be rather ugly by default. However, you can customize pretty much everything via editing your Xresources file.
In terms of advantages over gnome-terminal... it's lighter weight and considerably faster (though tbh, speed isn't that important for most people). It doesn't depend on any Gnome services/libraries, so it integrates better with e.g. a tiling WM. It's stable, in the sense of the developers won't cut <insert feature> out. The configuration is very flexible and it's extensible.
However, to be honest it's not for everybody. I wouldn't even say it's for "power users", it's really mostly for minimalists and the default configuration is incredibly sparse. If you're dissatisfied with gnome-terminal, I'd probably recommend roxterm or lxterminal instead. IMO, urxvt is more one of those "I already know I want it and I know why I want it" kind of things. That said, I've been using it for a few years and I really like it.
* not the only one, but I'm not sure finalterm is really ready to use yet, and it's certainly not lightweight.
Edit: Hmm, it doesn't seem to work properly in 9.20. Well, I should probably be using tmux anyway, which does fix the problem.
As simple as possible, and no simpler.
It does nothing that impresses other terminal authors. Other terminal authors seem to prioritize user experience beneath keeping up with the achievements of other terminal authors. So it is completely incapable of 3-d widget animations, or transparent viewing of 3-d accelerated VDPAU movie rendering via transparency, or any number of things that are extremely technically challenging and "desktoppy" and very impressive to other terminal authors but users primarily see as something that makes it slow and crash alot and complicated and distracting.
To quickly try it with a larger font size, you can do urxvt -fn 'xft:Dejavu Sans Mono:size=10' (but it's usually configured through X resources, see the urxvt man page)