I guess so. For their display needs, it seems to be doing the job well. Without a CMS, you can achieve something similar in terms of easiness and effectiveness by managing your layout blocks (header, left panel, main content, footer, etc.) in separate php files, and using include() function to build your pages.
After reading the source code looks like created with Dreamweaver because of this tag, <!-- #BeginTemplate "/Templates/default.dwt" --> Code (markup):
you think it's the best? Do you know any example sites that are similar to what I'm after and are using it?
I do think it's the best, yes. Can't remember any serving particularly as a mobile phones portal but you can look around. Google for "Joomla powered websites" to get an idea.
When speaking about Opensourcecms let's just call it Joomla Easy to install and use, takes about 2 minutes on localhost to install. Can anything be easier than that?