How sophisticated are your users?  One problem is getting through firewalls.
Can they set up proxies?  What version of Java do they run.  If they have a
runtime that predates 1.4.2, then they have to install Web Start themselves
or upgrade to 1.4.2.  Can they do this?

I used this for a fairly controlled group of users, inside the firewall.
Often they did not have a current version of Java on their desktop.  Even
though they are DP personnel, they may not be Java literate.  Sun provides a
sample web page which contains a JavaScript which can detect the level of
Java that you run in your browser and pops up a link to their site allowing
you to download and install Java.  This can be a fairly heavy exercise for
the unsophisticated user, even in a corporate DP environment.  There was
lots of handholding involved, more so when management was involved.  Also,
there were mainframe and Unix developers who only had terminal software and
basic Microsoft office software installed.  I found they had no
administrative privileges on their own desktop machine and could not install
the JRE unless some one with admin rights did it for them.  All this after
writing detailed instructions on how to install the JRE, some people refuse
to read instructions.

Provided the user had a , installation of the applets was a snap.  There
were few calls about the certificate download, dialog box.  This was in the
user guide, but as I said before....  The applet install was much less
traumatic and it was great then wanted to add new features, since we didn't
have to send and installation instructions and patches.  This was all done
automatically and we had a nice fat client that we could enhance on
everyone's desktop.  Upgrades are the best feature of JWS, since having to
shuttle jar files and explain classpaths and wonder what was already in the
user's classpath were taken care of.  This takes a lot of pressure off of
servers since we didn't have to deliver content such as with JSP with each
request, just the data.  Requests involving databases could be done directly
from the client (remember this was inside the firewall).  Overall this was a
great product for use inside the firewall.

Outside the firewall, you have a lot more considerations like security and
maybe the level of user who is you audience.  You have local firewalls that
you have to content with once you are outside the browser based security.  I
guess its like any desktop product you deliver, accept as I mentioned in the
beginning, you may have Java versioning issues to deal with.  Not a stopper,
but be prepared to get some calls.

Once we had the kinks worked out