I'm a contractor and don't stay for the after-effects of the installation.
The engine is getting a bit long in the tooth, the UI should be redone to be a bit more modern and flexible. The software has been running pretty much on the same UI for a long time.
The self-service UI was not a good enough improvement due to the "self-only" part. Lately there's been improvement, but other vendors seem to have much slicker UIs. Users want wizard-like UIs nowadays (in my experience). They don't want to navigate endless menus and selections.
The engine is still the same clump of Java it was long ago as Enrole. But now it's a notably larger collection of extensions, and IBM has it reasonably documented. When done correctly, customizations are stable, but when done incorrectly they may cause hangs in the database that are difficult to resolve.
Outside of that, the Adapter Development Tool (ADT), an old and (officially)
unsupported tool made and maintained by an IBMer seems to no longer be maintained. A lot of people used this tool to create customized adapters for ITIM, expanding it further than IBM ever could. Now it seems all gone.
I have used this solution for 15 years.
In older versions there were some stability issues, but not much in the new versions.
In older versions the DB clustering was not easy, but that has been fixed long ago.
The technical support is slow and inflexible. Occasionally, a good techie will help above and beyond, but it seems that the incentives no longer support serving the customer like they used to.
In earlier versions, the setup was complex. Now, you can set it up easily, especially the appliance.
I was working for IBM at the time and had no choice.
This is not a good product for a small implementation, but a great product for medium to large implementations. Consider if you need all the goodies in the feature list and if you're willing to pay for them.