We have used Neo4j in microservices. In one of the microservices, we used Neo4j since we have some requirements similar to MongoDB plus Elasticsearch. It performs both functions. Instead of doing those two things, we use Neo4j's in-built Solr for queries, and it has MongoDB-like features. We have used these features as well and found them beneficial.
For Neo4j, we have used it for smaller applications. I have not tested it with larger applications or big data. Our clients use it for applications with 200 to 300 customers. We have a limited database yet did not find any performance issues.