What do you like best?
The best part of ITAM (now ISAM) is undoubtfully the fact that it can integrate in a big IBM security infrastructure. Of course it gets the job done and allows a pretty good control over accesses, the SDI software capabilites that come along also are a plus since they allow for good control over your whole LDAP environment.
The last features implementations in the version 188.8.131.52 are simple but quite important making life easier for IT deliverers (especially the network implementations).
What do you dislike?
The appliance version to where it is headed gives very little control over the system, this also means that the integration is of course easier. But one of the big upsides of ISAM is it's elasticity so not being able to fully control the system is often a big problem.
Also on a point-to-point comparison, ISAM could fall short if compared to other products, it's plus is really in integration with a more wide IBM security suite.
Recommendations to others considering the product
Think about the full picture, consider a wider IBM security solution to have full advantage.
What business problems are you solving with the product? What benefits have you realized?
Control over accesses, if correctly integrated we also managed to have full visibility over identities and user id syncronization and management (thanks to ISAM-ISIM/IGI integration)