I have been an avid user of Mambo and now Joomla since 2001. taragana.com is designed using Joomla. Unfortunately we haven't been able to maintain the site very well, our fault not Joomla's.

I wanted to re-design the site to highlight our products and service, and to cope up with our plan for several micro-site development in 2008 in addition to delivering a nice look. Let's look at my 5 simple requirements for CMS:
1. We should be able to easily embed custom code (php) to embed widgets (or snippets as Modx likes to call them) in certain pages.
2. We should be able to easily modify the pages, preferably from the page itself (think AJAX editing).
3. Ability to create micro-sites which differ structurally and functionally from main sites
4. Flexible hierarchy and menus
5. Automate Sitemap (Google & regular) & RSS feed generation, nice permalinks & SEO optimized URL

Joomla as always is pretty inflexible if you want to think outside Joomla box. To incorporate php code in Joomla you will have to use a plugin like Jumi, which works pretty strangely when it works. Personally I would like something simple & reusable. Modx allows you to incorporate (and reuse) snippets in documents which are essentially PHP code. Similarly you can use chunks to incorporate to embed static reusable html content in your documents. Chunks can contain snippets too.

Modx allows you to edit a page directly from the page itself along with other functionalities by automatically adding moo Javascript library for logged in users. This is a nicety I never had in Joomla / Mambo. You will love it once you get a hang of it.

Writing custom Joomla / Mambo code is no-mean task for a newbie. The documentation is often out of date and it often looks Martian even to a veteran like me. I wouldn't ask a web designer to touch it with a 10 feet pole. Mambo / Joomla reeks of over-design and is heavily over architected (feedback welcome). What lured me to Modx was simplicity. With two major versions and drastically changed style of developing templates, Joomla have become much more complex. Personally the new template tags were my single biggest turn-off. However that is just one of many in the bigger scale.

Modx doesn't have all the add-ons that Joomla has. However it compensates for it with its simplicity & ease of use.

Modx is SEO optimized from ground-up. The pages are SEOized (title is hypenated to form the page url) like WordPress nice permalink mode. You can individually customize the meta tags for each page.

The pages in modx uses a template which can be different for each page. This allows you to easily create micro-sites within your main site.

As soon as I hit the limitations of Joomla, I started looking for alternatives and Modx stood out among hundreds of others because of user enthusiasm of this product. I decided to try Joomla and I am happy to say my designer is happy with it and so am I.

In Modx, like Magnolia, you can see a view of the hierarchy and you can perform actions on the items from there. Modx containers are much easier to understand than Mambo section and category.

Compared to Modx, learning Mambo / Joomla looks like rocket science; I kid you not. Try it and you will know what I mean. Modx also has plugin, but I haven't needed it yet. As far as taragana.com is concerned modx rocks my boat.

I can safely predict Modx will be the CMS of the future, leaving Joomla / Mambo far behind unless they catch up with documentation and focus on simplicity instead of complex design as it is now. Modx is Ajax all the way. All it needs now is a super-strong community like Mambo / Joomla to fast-forward it to the future.