Pros
Benefits are great. Typical bigger company benefits like 401k, better medical plans, etc. Some parts of the organization are healthier than others, most of it is determined by the VP in charge and how mature s/he is as a leader and visionary. VP spots are tenured, so plan to actively work to move to another if you find yourself under a dud. Coworkers are smart and nice on the whole. The company encourages friendships and this is easily done at happy hours and other events.
Cons
Senior management has become out of touch with the lower ranks, most notably Dr T. All the vice presidents are actually "yes men" (okay there are *finally* multiple women vice presidents as of 2015...only 40 years in since the company's inception; can you say good Ole boys club?) For US based employees it is doubtful there will ever be any more glory days. Plan to watch more and more jobs go overseas. You'll be waking up early to work with European countries and staying up late to work with Asian countries. Work life balance that supposed to be amazing only exists if you are in engineering. Any other part of the organization you can expect to work a typical 50 to 60 HR week. Finally, know that if you have worked at NI longer than 5 years your salaries are compressed. This used to be compensated by the incentive stock options, but now that they have changed to restricted stock options much fewer people are given any reason to stay.