Pros
Most fellow employees are very nice and talented. There's a chance to learn from different areas of knowledge and meet external interesting people. Remote work is common.
Cons
Stephen Wolfram (the CEO) creates a toxic working environment due to his constant use of verbal abuse and bullish behavior that knows no limits and thinks he's changing the world and everyone should use the Wolfram Language for everything...and yes, even when he had the chance to use cool names for his products, they all end up being named Wolfram *Something* and not even the employees can tell the difference between products or understand what they are for. Although the Wolfram Language is good for prototyping, mathematical work and some data handling, it's useless for production quality development and the reason a lot of Wolfram technologies are unreliable or inefficient is because Stephen Wolfram wants everyone in the company to use his language even when there are much better (free) alternatives. He's a terrible CEO, knows nothing about marketing and has a twisted sense or reality. That's why the company is in decline. If you happen to work on a project Stephen Wolfram fixes his gaze on, be prepared to hear constant offensive language and abusive treatment from him. Internal technology is primitive. There are many good alternatives but Stephen Wolfram doesn't want to pay for them. Forget about using a Google product because he openly hates Google. Salaries are well below average and you are very lucky if you happen to receive a bonus at the end of the year. Stephen Wolfram will do his best to keep your salary as low as possible or come up with excuses not to pay entry level employees. Communication between teams is very inefficient and you'll end up being harassed by Stephen Wolfram because of other people's mistakes. Although Wolfram is a name that still holds some respect in some areas, it is basically an unknown company and the skills you develop there are useless in the outside world.