Pros
Never get bored. There is much to learn and plenty of places to grow. People are promoted within the company with regularity. Education is a prized asset, and they promote it by subsidizing your tuition. Lean Six Sigma Green & Black Belt training is also heartily encouraged. On a personal note, the people I've interacted with have been extremely competent, very likeable, have high standards for performance, and are open to sharing what they know or have learned while working there. Other perks, on-site gym, gym membership discounts, cell phone discounts, MS Office deep discounts, ski package discounts. To other local employers, PACCAR has brand recognition that stands for quality.
Cons
The cultural environment is not for everyone. Suit and tie for the fellows. Being clean-shaven also appears to be a requirement. Tailored dress clothes for women. No sandals. At times, the dress code seems oppressive on those mornings when you wake and say to yourself, 'I really just wanna be in jeans today."