The maturity of Kundera can be best projected by the following (from github) :) :
Subscribers: Thoughtworks, Alibaba, XIOAMI, Filpkart, DataStax, Teradata, etc.
Forks: Accenture, Hortonworks, Cisco, Intuit, eBay, Ericsson, etc.
Stargazers: Apple Inc, Facebook, Twitter, Redhat, Adobe, Morgan Stanley, HUAWEI & many more.
As of the companies which use Kundera, you can check its
Production Deployments. Also, Walmart in one of its groups uses Kundera.
You can create a basic Kundera-Hbase project to have clear understanding about the architecture and data modelling. Following are few useful links:
Thanks and regards,
Karthik.