<p>A few years ago client Java was unsuitable for web development because a remarkable part of web users did not have Java installed. ( I don't remember exact numbers, more than 10%). </p>

<p>Now I see the Google Analytics stats for a big site and it tells that >98% of users have Java installed.</p>

<p>Is these stats very biased by Javascript usage? As I understand Google Analytics measure only users that has Javascript.</p>

<p>Is the picture similar on other big sites?</p>

<p><b>Does client Java have really "stopper" drawbacks compared to Flash?</b></p>

<p>EDIT: I mean java applets mainly, java WebStart seems to be not suitable for average user.<br>
I mention Javascript only to describe the way Google Analytics works.</p>

When I wrote my diploma project, I had to choose between Flash and Java Applets. Here are some pros and cons:
Java Applets:
[plus] you program in Java, which is mature and stable
[plus] you can use the Java GUI frameworks that pack a lot of punch
[minus] the first time the user hits the page with the applet, the JVM must be initialized and this can take up to a few minutes even on a fast computer
[minus] Applets are not meant to be used as animation media; sure, you can do stuff, but it is like programming in C - you do everything from scratch
example: i needed to show a data packet as it moved between two routers. The packet must be a control of some sort, like a button or smth. This animation can be defined in 1 line of code in Flash, where all objects derive from some base object that can be animated. I could not find a suitable solution in Java.
Flash:
[plus] really really focused on animations;
[plus] ActionScript is actually an OO language
[minus] ActionScript is sloppy, bughish and has only a few supporters. If you are stuck, be prepared to search obscure Japanese forums for solutions
[minus] ActionSCript may be OO, but it lacks a lot of features, like Enums, fully fledged interfaces, threads (!!!!) etc.
[minus] Flash was designed to be used by non-tech people - they just use the authoring tool; I wrote code for everything and it worked, but it was a pain.
My conclusion:
I eagerly await a programming paradigm for animations and rich client interfaces.
ps: Silverlight seems to be a disappointment so far, maybe Microsoft will inject some $ into it.