The interview process is like that at other tech companies. Initially, it starts with a phone interview (with the CTO), which isn't really too technical. It's mostly an introduction to the company, an opportunity to get to know you, with a tiny bit of basic knowledge questions. If they like you, they will offer you an on-site interview. This could be done right there and then. They do accommodate your timing as needed.

On-site interviews get straight to the point with technical questions and don't waste too much time.

The interview process itself was fine. The fact that the company is quick about telling you the results is much appreciated. They aren't like other companies where you have to wait weeks before knowing the outcome, which is definitely a plus.

Very low-level questions about Java.

This goes beyond just how a particular thing is used, but delves into why and/or where it can be used.

It requires a deep understanding of the language that you may be familiar with.