Recommendations to others considering P4:
If you are looking for an enterprise grade, highly scalable and expertly supported centralized source control management tool, Perforce is the best there is. If decentralized SCM is preferable or then Git is a great option as well, but know that Perforce also support DSCM capabilities as well, along with excellent integration with Git repositories, again with excellent support. Review collected by and hosted on G2.com.
What problems is P4 solving and how is that benefiting you?
We migrated off of Microsoft Visual SourceSafe in order to make user of the concurrent checkout and branching abilities of Perforce. This was back in 2007. The benefits however extended far beyond the core benefits that the system provided us. Whereas in VSS most development was performed against the main trunk of development (development occurred on mainline in Perforce parlance), we could begin to practice stable mainline procedures within Perforce where development would take place in development branches and once vetted through a build and QA system, promoted to mainline once deemed stable. The "copy up, merge down" process allowed us to further ensure the integrity of our mainline and allowed for development branches to catch up with mainline when it changed.
We have not implemented Streams because they do not currently fit into our use of the system, but provide yet more ability to enforce process on the movement of code and maintaining the correct hierarchy of codelines.
The various tools that come with Perforce out of the box such as the Merge tool, Revision graphing, stream graphing, distributed source control, Time Lapse Vies, etc are also a boon for developers as it allows them to track down where modifications to a file were received from, and by whom.
It has also allowed us to improve our resilience through the use of replication servers, proxies, and in the future Edge servers (where remote sites can hold their own set of metadata [database] files while still syncing source to the primary server). Our checkpoints can happen nightly against the replica server, leaving the master server online to continue to serve users non-stop.
And of course, I'll mention for a third time the Support team at Perforce, which is absolutely fantastic. Review collected by and hosted on G2.com.