Pros
NI's a great place to work for a few reasons but most of it comes down to the people you get to work with and the responsibility/opportunities for growth that you're given. I started in the ELP (Engineering Leadership Program) and have had a ton of opportunities in a short period of time. I can't imagine any other employer giving me the chance to own important tasks or make such an impact on the organization. Where else does the CEO sit with random people at lunch to chat.
Cons
Like I said, it all comes down to the people you get to work with. There are some incredible people at NI and the organization's flat structure allows for you to interact with them easily. Unfortunately, there are also those that you would prefer not work. Not everyone can be perfect but a few of these "bad apples" do spoil the otherwise excellent work environment.