Is joomla good for website design clients?

Joomla's does have a bit of a learning curve when it comes to management of the site hierarchy. Submitting, modifying and deleting articles on a Joomla CMS setup is relatively easy, and can be learned with a quick morning training session.

When I would present CMS options to clients as a consultant, I would always include in the quote time for training and technical support. It is definitely not a product that just anyone will pick up and master without thinking, it will involve a bit of training. All that said, it is an excellent option to provide a client who wishes to be able to have updates at their fingertips, you should just make sure that they are aware that using this CMS, or any CMS for that matter, does take a bit more expertise than a standard user may have. They won't have to be a power user by any stretch, but they will need to be a less timid user who isn't afraid to explore what's behind all the buttons.

I would also advise providing a good deal of literature and documentation to any client that you offer a CMS set up to.

I actually recommend WordPress for clients with little or no web knowledge because WP is easier-to-understand and there are less things in WP for them to mess up.

Joomla is awesome if your client knows a bit of what he's doing and/or doesn't get frustrated easily.

If you set up WP properly, your client will have the freedom to change themes, sidebar widgets, page contents, etc.

Yes 100% this is what its was designed for

You will need to learn the templateing syntax for php they use and most likely the plugin api so you can extend it

yes we have tried it many times