Pros
Some of the smartest and most capable engineers were people I met while at the company. The passion and talent here is among the best in the business, which makes for a great environment for personal growth, since there's so many people to learn from. The office vibe is also very nice, encouraging creativity with a laid-back touch (however, the "Friday music" tradition practiced in some offices is a notorious annoyance). The company culture, especially in the two big offices (Stockholm & NYC) is a bit like a university, with social events, interesting and intelligent people walking around, and a creative/inspired vibe. Spotify is building product on a huge scale, and does a very good job of trying to build this product based on data analysis. The company claims that numbers and analytics are the best arguments, and for the most part, this is true. The company culture is extremely self-critical (sometimes to a fault), and discussions about faults within the product, workflow, office culture, etc. are openly and bluntly discussed with a constructive tone. People talk about problems because they want in earnest to find solutions to them, not to just cynically complain.
Cons
As the company grows, it is having a difficult time reconciling its traditional Swedish roots with the challenges of managing a large multi-cultural, multi-office. The result is that employee input is solicited frequently, but then seemingly ignored. Similarly, product design is a very top-down process with little room for individual freedom of work. If you have a great idea for the product, be prepared to work on it after hours and weekends to make it happen. The company has annual "hack weeks" to encourage innovation, but in practice, it's difficult to get these hacks released without buy-in from product owners. The number of amazing hacks that I saw created and then never released to the outside world are too many to count. There's a strong agile culture at Spotify, which unfortunately falls in the "cons" category. A large number of agile coaches roam around the company, but their actual responsibilities are extremely unclear and getting them to do actual work is nigh impossible (even meta-work, such as organizing a squad dashboard or the bug tracker). In the worst case, the agile staff impose ridiculous time-wasting activities and frequent meetings with large invite lists. Some teams manage to take matters in their own hands, and these tend to be the highly productive ones in the company. Company priorities shift rapidly and widely. This is partly due to the very fast-paced and competitive world of streaming, and Spotify has done well to shift company resources rapidly enough to beat off all competitors. But from the inside, this sometimes feels like "the next big thing" dominates the entire office just long enough for something new to come along and displace it. Many of the older and ill-maintained efforts pile up into a slow and steady burden of external support and tech debt (though to be fair, the company is very good at managing and eliminating tech debt). There is also some troubles with career advancement at the company. To the credit of upper management, this was identified as a problem and they introduced a program to address this. However, the end result of this is a vague series of "steps" in which most engineers agree that advancement means being shifted towards management and out of engineering. I'm not sure how non-tech sees these issues, but regardless, attempting to shoehorn all company roles into a single generic career advancement model reflects the lack of understanding at the heart of the matter.