Pros
I think the best thing about Stamps.com in a word is opportunity. I've heard stories from and seen the way they strive to offer advancement opportunities to their employees. This is truly a place where you can grow as long as you're willing to grow as an employee. If you see a career path within Stamps and you gain the skills to follow it the door is wide open for you. They invest in you and give you the opportunity to invest with them and in turn yourself as well. This COVID pandemic has really shown me what a great company this is. The many horror stories I've read in the news and heard from friends is a far cry away from the care and support Stamps.com has shown for its employees. I can't say enough. Its no wonder why there are people here for 10 and 15+ years. Even if I don't become one of them I think the majority of people applying would find a happy home at Stamps.com.
Cons
I don't think I could add anything here that wouldn't be what you'd normally expect from employment at a semi-large company. From my perspective the good outweighs anything I could point to as a con.