We've used SharePlex in two capacities. Its primary use is to provide heterogenous replication of production data into auxiliary systems (data marts, data lakes, BI, analytics). That has been an ongoing use for several years. We initially used it for Oracle -> Oracle replication only but have since extended its reach to utilize newer features that allow replication to SQL Server and JSON targets.
Our secondary use of Shareplex was to facilitate a major, complex database migration. It enabled us to migrate to new servers, new storage, update the OS, upgrade the database version, and apply critical patches with little (literally a few seconds) of downtime. We were able to run the old and new systems side by side and compare performance prior to the migration. It also allowed us to provide fail-back capability in the event of an issue, without data loss.