I love JSF, but let me be realistic about it.   There were many kludges
in 1.0, and gave itself a bad name.  1.1 works better, and the up and
coming 1.2 is going to be a fireworks show as to what it can do with
AJAX components.  We will see a rush to learn JSF due to these AJAX
components and people will then have an appreciation for it.  Sun
Studio Creator is open source and free now, and I think that will help
bring even more popularity to JSF.  JSF is also an up and coming star
in the job market too, so won't be doing a disservice to you by
learning it.

Obviously, Struts will be around for quite some time... but yes, it is
becoming less popular for new development.

That's a shame.  JSF 1.2 will be a huge improvement over the current
version, but it's still far and away superior to Spring MVC.  Spring MVC
is rather unimaginative in that it forces you back into the same
application structure as Struts did... and it comes with the added
disadvantage of an ideological dependency on the core Spring concepts.

I've seen a fair amount of interest, and a moderate to low number of
development projects actually using it.  Unfortunately, JSF 1.0 was more
of a proof of concept than anything else.  Someone forgot some important
design principles when it was written, and it was rushed to market too
soon to properly handle the interactions with JSP.  Nevertheless, those
problems are being solved, and the interest is still there.

The JavaServer Pages or JSP has been a defact
standard of JSF view technology and same time
been an huge fetter both for JSF application
development and cusbom JSF component
development.

Lately, however, the heavy iron dumbbell is
going to be taken away from the feet of JSF
by the advent of the Facelets technology
invented by one of long time JSF EG members.

I recommend to read:
http://www-128.ibm.com/developerworks/java/library/j-facelets/
http://www.jsfcentral.com/articles/facelets_1.html