What do you like best?
Definitely seems like a more developer-friendly tool, and integrates well into our deployment workflow. The modular approach to content is an interesting one, and for certain types of websites it would be a killer feature.
What do you dislike?
From the editor's perspective, Contentful is maybe a bit TOO developer-friendly, as it lacks a lot of the basic features that I look for in a CMS.
While it may be highly configurable, it puts the onus on me to repeatedly ask our development team to add or change things at a platform level, rather than giving me the ability to do so myself. Instead of empowering my team to do more without the intervention of the dev team, it's simply changed the nature of our requests to them.
Recommendations to others considering the product
Do your research before you invest time in set up. For a mostly technical user base that can tweak and refine on an ongoing basis, Contentful might be a great option. For an organization with more robust editing needs, it may fall a little short.
What business problems are you solving with the product? What benefits have you realized?
We didn't have any CMS in place before, so having one now has made posting and editing content easier for us. The biggest benefit is that the learning curve for Contentful is pretty low, so it's pretty easy for us to onboard new members of the team.