Tim ffitch (1/21/2016)
I can see where this would be useful for multiple environments on the same server. When dealing with multiple servers then it would be better to create your environments in Data Tools/Visual Studio using package and project parameters with different values set up for each server. This is one areas where 2012 is so much better than 2008.
This is a useful technique for handling connections for development purposes. But does it give you everything that environments give you? A few potential negatives come to mind:
1) Where you have many SSIS projects, if a config item (eg, a conn string) ever changes, this requires (potentially) only a single change in SSISDB when using an environment, not one change per project.
2) Sensitive items are not supported.
3) Config changes require code changes.
If the answer to your question can be found with a brief Google search, please perform the search yourself, rather than expecting one of the SSC members to do it for you.