Recently I re-created a System Center Configuration Manager 2007 (CM07) server build in my lab. It was not something that I looked forward to because after using CM12 for so long, I was spoiled.
CM07, although easy to install, is a pain to work with. There are far too many hot fixes to install, and at least three revisions, the last being R3.
Comparing the functionality between CM07 and CM12, there are a lot of things in common. However, the real difference is how they go about doing this. CM12 has a much better and cleaner interface, and items are grouped in a more logical fashion. In CM07, it takes time to hunt around to find what you are looking for.
When it comes to speed, CM07 is slower than molasses. It takes forever to get captured data into the database, and even slower to have SQL views created. In comparison, CM12 floats on air. SQL views are created right away; the sms_def.mof was moved into the console and can be controlled with the GUI.
If you are still a CM07 user, I highly recommend upgrading to CM12. Take that old CM07 environment and bury it!