As many organizations are beginning to transition from Legacy versions of SharePoint to either the latest version of SharePoint (SharePoint 2013), or make a move to a SAAS offering (SharePoint Online), there are many considerations that should be analyzed before making the big jump.
Fab 40 Templates
When SharePoint 2007 was released, Microsoft made available 40 different Site Templates to help provide additional functionality to organizations that were deploying SharePoint 2007. These Site Templates had various different functions, including Help Desk, Financial, and Training Templates, to name a few. The Templates were provided for free by Microsoft, and actually helped accelerate the ease of use for organization who were looking to leverage SharePoint as a platform for these functions. The only problem? With the move to SharePoint 2010, Microsoft discontinued any support for these templates.
There was an effort however to make compatible versions of these templates with 2010, to help ease the upgrade process from SharePoint 2007 to SharePoint 2010. And for the most part, these new templates were able to help bridge that gap. With SharePoint 2013 however, the templates were practically unusable with upgrading from SharePoint 2007 or 2010. This is now one of the biggest upgrade considerations if your organization deployed and leveraged these templates extensively. Due to the new Architecture in SharePoint 2013, the templates will most likely not function and therefore, any sites you may have created will need to be completely redesigned if you are planning on a database upgrade from SharePoint 2007.
So, you deployed SharePoint 2007, but wanted the site to reflect your Branded style for your organization. During that time, you may have had plenty of custom branding implemented to “Make SharePoint not look like SharePoint”. Unfortunately, due to the changes in web standards, browsers, and overall rendering performed by SharePoint, your custom look and feel may not translate to the latest version of SharePoint. SharePoint 2013 implemented a new way to create a customized look and feel that marries the latest web standards with ASPX Master Pages, that is a complete departure from previous version of SharePoint. As newer web standards have allowed browsers to render styles in a much easier and more efficient way, this is not a bad thing! But when upgrading you definitely need to be aware of this issue, to ensure that when you are ready to upgrade, you have a branding strategy that can be implemented with SharePoint 2013 or SharePoint Online.
Custom Application Development
Since SharePoint 2007, the .NET framework has gone through 2 Major version revisions, and 2 minor ones. While this may not seem like a lot, in terms of that framework, the differences are night and day. If your organization decided to develop custom .NET applications to run on SharePoint 2007, there is a good chance that those application may not be compatible with SharePoint 2013, and probably a 99% chance that they cannot be ported over to SharePoint Online. With SharePoint Online, there is no access to any Server side code, therefore any Timer Jobs, Full Trust Solutions, or custom identity providers you may have in place, will need to be completely redesigned. With an On-premise version of SharePoint, you still have access to all of those options. However, your application may not work with .NET 4.5, or may be leveraging deprecated web services that no longer exist. Since every application may be unique, a full analysis on compatibility for SharePoint 2013 should be at the top of your list.
With the release of SharePoint 2013, Microsoft has implemented a new way of developing for the platform that they refer to as the “App Model”. This places a much larger emphasis on developing using Client Side API’s instead of Server side. This allows code to run in either an on-prem or cloud based offering (especially SharePoint Online, as they don’t allow any Server Side code execution).
So, your SharePoint 2007 environment was fairly Vanilla, and mostly used just collaborate on Documents. This can certainly make your upgrade path much easier, but the important thing to note, is that you cannot upgrade directly from SharePoint 2007 to SharePoint 2013. If you want to upgrade the SharePoint 2007 content databases to SharePoint 2013, you will first have to detach and reattach them to an interim SharePoint 2010 farm, run the upgrade process there, and then detach and reattach them to your SharePoint 2013 Farm. (Note: this does not apply to SharePoint Online. I recommend a 3rd party tool to migrate your content directly from 2007).
With every upgrade or migration, there can always be challenges to getting to the latest and greatest. Performing a thorough analysis of your existing environment is a key activity to ensuring your project will be a success!