Met NI recruiters at university career fair. Was later contacted to interview the following day. Interview was straightforward and lasted about an hour. Interviewer started with some personality questions (give me an example of a time when you went out of your way to help someone, etc.) and then moved on to fairly simple technical questions. One involved connecting a microphone to a computer (testing for basic knowledge of ADCs and signal amplification) and another involved writing code to find a missing number given the other 99 numbers between 1 and 100. Interviewer then asked briefly about where I'd like to work within the company, and explained more about the available areas. Interviewer was very friendly and I felt like we had a good connection during the interview. He seemed interested in my thought process and worked with me on the technical questions, rather than simply grilling me.
Later received an email to schedule a follow-up phone interview with a different person who asked me in detail about why I wanted to work for NI, what I saw myself doing in 10 years, what I am most interested in doing at NI, what did I think about living in Austin, etc.
Waited 2-3 months before getting an offer, although they did check in once or twice during the wait.