Ventajas
Great work/life balance. Relaxed work environment. For a new grad, NI makes it very easy to get up to speed. There is plenty of training available and you are assigned a mentor to help you along. Early in your NI career, you gain more responsibilities probably sooner than you would at other companies. Job stability is rock solid, to the point that it's practically impossible to get fired. Your work load is never unreasonable.
Desventajas
Prepare to be underpaid for your skill set. Pay raises usually don't even keep pace with cost of living increases. Some years, pay raises are skipped altogether. Usually, NI prefers to hire more new grads rather than give raises to existing employees. Speaking of hiring new grads, NI has grown its headcount way past what was necessary. At this point, there are too many engineers and not enough work. The company is doing well in terms of revenue but it is so bloated with unnecessary hires that the company profits are poor. Low pay tends to lead to low expectations. Poor performance is tolerated. There is not much incentive to be a "rock star" employee. Your yearly bonus is not based on individual performance but rather company metrics. Everyone gets the same bonus as a percentage of your salary. Recently, the yearly bonuses have either been zero or so small that it's embarrassing to mention it to anyone. Again, the bonus is based on company metrics which are currently poor because the company is so bloated with employees. If you are an experienced engineer, you are not paid what you're worth. The general idea is that everyone is replaceable and, thus, if you leave, you will be replaced by a new grad. Much of the projects/work are such that a new grad or relatively inexperienced engineer can complete the work. There is not much need for a "veteran" engineer for much of the work. Deadlines are usually pushed farther out to accommodate lack of experience.