Pros
NI is a great place to learn everything from programming, to marketing, to leadership skills. Because the company is primarily made up of engineers, you have the opportunity to move into any discipline in the company if it interests you and you set your mind on it (if you are an engineer). The people are generally brilliant and the work environment is healthy. Senior management is conservative. The company has no debt and the customer base is very diverse. Their website is great at offloading transactional sales from the direct sales force.
Cons
Everyone complains about compensation, but very few people seem to leave. When you reach somewhere between 5 to 10 years, you will have learned a ton and be more than ready for "the real world." In fact you will excel there. NI hires the majority of people right out of college, which means most people have not worked anywhere else. Leaving the only place you know, especially if it is great (other than pay) is a scary proposition. If you are a top performer, leave. It is worth it. You will never be paid what you hope. Do the math ~$1B revenue / ~7000 employees = $143k per employee! That is before you pay for all of the other expenses, including the cost of the products you are selling, the building, marketing, NIWeek, etc. NI is a great place to work, but it's not the only great place. I'm thankful for my time at NI and I'm also thankful I won't be wondering "what if" after sticking around for an entire career.