The only business email option in my opinion
We signed up for Google Apps when it was still free, and have been using it every since. We have implemented other email systems for clients when they requested it, but not other cloud-based email service comes close to Google Apps in terms of features and integrations. That's why we recommend it to all clients who need a business email solution.
Features, flexibility, integrations. Onboarding has become super-easy.
Sometimes gets slow in the browser.
At the time it was free, and it allowed us to use the gmail interface with a custom domain. But six years later, we also pay for the service since we've evaluated other solutions and this is the best in terms of features and value.
Email and Google Docs for team collaboration on documents.
The ability to have email, chat and docs under one umbrella for our org is the only way I can imagine functioning.
Professional email that is efficient and feature-rich.