I've been working with JSF for 3 years and I can say that the most powerful thing about it is that it abstracts the communication between browser (form input or actions) http request and Java.
There are rich libraries available for JSF, like: ICEfaces, RichFaces, ADF Faces, PrimeFaces, which gives you a big amount of rich components that may be enough for you.
JSF tries to make development of web applications more close to desktop applications. It addresses the most common tasks for a web application (no matter the technology) and automates them using its LifeCycle.
However if you want in some cases a certain behaviour that's different from how a component works, you have to make some workarounds, or build your own components (which may be hard, except for composite components).
I have integrated JS successfully for tasks that didn't need to trigger some action in Java like select all checkboxes, hide/show some parts of the page, and so on.
JSF is very easy, yet very powerful, and requires a certain expertise for some tasks.
The last version of JSF, 2.0, addresses the common problems JSF had, because of its POST nature, so now I'm very happy with it.
Regarding users gestures like ctrl+click, the way web applications in JSF work is a little different than normal ones, buttons Back, Forward, Refresh might not work as expected sometimes. But hey, great web applications have the same behaviour: Try Ctrl+Click in PayPal .. or try Back Button in Vodafone.ro
If you want full control over your HTML, use plain JSP. But when you have a huge web application, JSF is a good option for Rapid Application Development(RAD).
