An upgrade project from versions prior to Dynamics NAV 2013 can be an easy task or a large project. It really depends on the amount of modifications that are done and the version of Dynamics NAV you are upgrading from. The basic principle is that the older the version, the more involved it will be for you and your company.
Summarizing, the processes to upgrade versions prior to Dynamics NAV 2013 are:
All these steps are done manually and some steps are very time consuming. There are horror stories of developers pulling all nighters just so they can execute the next step in the upgrade process.
It's not a very good use of time and money for both the partner and the customer. But this was how it was done when I was younger.