Pros
Travel the world and work with fantastic people on cutting edge technology. I can't stress enough how fantastic the people are and how they are at the core of everything we do. This has been stated in many a review here, but there's an 'essence' about TW employees which transcends geography, race, gender, background - no matter who you meet you get a consistent experience. I've heard this from new hires. Colleagues are very smart, respectful, and passionate about solving client and humanitarian problems through technology. Cool temperament, good listeners, and empathetic. Hobbyists across a huge number of areas both within the tech domain and beyond. Expect in an office to find hardware labs experimenting with the latest IoT theme; groups of people booking outdoor weekend activities (multi-day hikes/camping, ski trips, local community work), VR/AR experiments, continuous learning sessions for our inquisitive graduate recruits, internal projects, meetup groups... Despite being a medium/large global organization with over 3000 employees, TW maintains a local feel by keeping each office under 150 people. This creates an environment easy to navigate - people can keep their network local having little interaction with other offices, or chose to branch out to other offices, even countries, to expand understanding of different markets. Taking assignments in other countries (e.g. 1 year) is supported in most cases, acknowledging the importance of understanding cultural and market differences, and how travel can enrich character and build soft skills. Agile, DevOps, Continuous Delivery, Lean startup techniques are all at the core of how we work. These aren't areas or disciplines TW has decided to adopt or practise - they have been developed and/or evolved by our folks. The organization is 'flat' - very few levels - which introduces many different career paths. Employees are encouraged to think hard about how to develop own skills and self-improvement plan. ThoughtWorks has a long history of writing books and speaking at conferences - huge support available for this.
Cons
Likely a bi-product of a flat hierarchy (we have 4 progressions from grad to Principle) a lot of self motivation and perseverance is required to instantiate and maintain new initiatives, communities, get idea traction. Some people despise 70% travel expectation - and it can be more (and less!). Exceptions occur all the time and each case is considered independently - there are no hard/fast rules. However its one of the most common reasons for people leaving. Other reason for attrition: engineers want to own a codebase and be responsible for maintaining it - seeing all projects through to completion.