Last weekend the Dutch Joomla!Days 2011 were held. All four ThemePartner core members went to check it out and we also gave two presentations. Such an event is always a great opportunity to talk to other Joomla! users and learn what obstacles they are facing in the Joomla! world. I noticed that some were wondering what to do when a new version of Joomla! is released. Questions such as "Should I upgrade to Joomla! 1.7?" or "Will Joomla! 1.7 be backwards compatible with Joomla! 1.6?" were heard several times. I think it is safe to say that the new release schedule of Joomla! leaves some people puzzled with what they should do.
Photo credits: seier+seier
Previous versions of Joomla! were released when a specific set of new features were ready. This way it could take years before a new Joomla! version was released (take version 1.0 to 1.5 for example, that took almost three years!). This has been changed and (inspired by Linux distribution Ubuntu) new Joomla! versions are now released every six months. Every eighteen months, a so called Long Term Support (LTS) version is released. LTS releases are supported for three months after the next LTS release. The advantage of an LTS release is that you don't need to upgrade to a next major release that often.
The next LTS release will be Joomla! 1.8 (or perhaps Joomla 2.0 as it will most likely mark a new era in Joomla?) which is supposed to be released at the 10th of january 2012, which is exactly 12 months after the release of Joomla 1.6. This means that if you deploy a website on Joomla! version 1.7 you'll need to keep in mind that after about six months no new security fixes are released. If you're the administrator of many Joomla! sites this can have a big impact. Joomla 1.5 will be supported until april 2012 as it is marked as an LTS release. You should ask yourself before upgrading to Joomla! 1.7 (or version 1.6 of course) if there are any features in it that you really need. If your site is running fine on version 1.5 and you don't need any of the new features then there is no real reason why you should upgrade. And if you decide to upgrade to version 1.7 (or any other non LTS release) you should be aware that after approximately six months you probably need to upgrade.
At the Dutch Joomla!Days 2011 both Brian Teeman and Ryan Ozimek mentioned that the Joomla! team tries to keep version 1.7 backwards compatible with version 1.6. There aren't any guarantees that it is fully backwards compatible, but if it isn't I don't think upgrading to Joomla! 1.7 will be as hard as upgrading from 1.5 to 1.6.