The most helpful aspect is it has helped us manage our certificate lifecycles better than ever before! It also creates more accountability for users with regards to their certificates as well.
I wish there were some tools in place that made managing multiple vendors easier; however all things are good when you find them so this really isn't much different from any other software out today. We've found great success using SCTLM thus far - we're able to have an easily accessible way to track everything regarding key management within one system rather then having 2 or 3 separate systems which helps lower costs by not needing additional support personnel etcetera.