What are the main disadvantages of Java Server Faces 2.0?

Question

Yesterday I saw a presentation on Java Server Faces 2.0 which looked truly impressive, even though I am currently a happy ASP.NET MVC / jQuery developer. What I liked most a

Answer 1

1. Inexperienced developers usually will create applications that are painfully slow and code will be really ugly and hard to maintain. Its deceptively simple to start, but actually requires some investment in learning if you want to write good programs.
2. At least at the start you will often "stuck" on some problem and will spend more time reading balusc posts on internet than actually working :) After a while it will be less and less of that, but it still can be annoying.
3. Even more annoying when you find out that the problem is not due to you lack of knowledge/mistake but actually a bug. Mojarra was(is?) quite buggy, and another layer of components adds even more problems. Richfaces was biggest piece of crap software ever written :) Don't know how it is now on version 4. We have Primefaces which is better, but still you will run into bugs or lack of features especially with more exotic components. And now you will need to pay for Primefaces updates. So I would say its buggy but its getting better especially after 2.2 version fixed some problems with spec. Framework getting more mature but still far from perfect (maybe myfaces better?).
4. I don't find it especially flexible. Often if you need something very very customized and there are no components that does that - it will be a bit painful. Again I'm talking from average developer perspective - the one with deadlines, quick reading tutorials, and searching stackoverflow when getting stuck because no time to learn how it really works :) Often some components seems to have "almost" what you need, but not exactly and sometimes you might spend too much time to make it do something you want :) Need to be careful in evaluating if its better to create your own or torture existing component. Actually if you are creating something really unique I would not recommend JSF.

So in short my drawbacks would be: Complexity, Not very smooth development progress, buggy, inflexible.

Of course there are advantages too, but that's not what you asked. Anyway that's my experience with framework others might have different opinions, so best way is to just try it for a while to see if its for you (just something more complex - not naive examples - JSF really shines there:) IMHO best use case for JSF is business applications, like CRMs etc...