Was using my own redmine cloud server instance but wanted something more stable and easy to manage for a corporate envioronment. Looked at Planio and another company. Both good, but the Planio UI is a more familiar redmine look and feel. The price plans are good, they actually have a free bronze plan which they don't advertise - good for 1 person operations. The customer service was very good. They were able to pull in my tasks from my old instance into the new instance, overnight. Then I had a couple of questions, and they always answered within a few hours. Note that they are in Germany so a question in the morning (US) might be answered same day, but one in the afternoon not until the next day. Response times seem good, so far anyway. I really like that they give you the repository for free - install tortoise on your clients and you have a managed, versioned, cloud repository in no time. Awesome. Oh, and the agile boards are included as part of their standard plans, which are very useful.
All in all, extremely happy. Always liked redmine, but using planio to manage/host that is a no brainer. Have used redmine before in projects large and small, and once people understand what it is, productivity goes through the roof. I would say it doubles effective output. Many people don't understand what it is - they think that servicenow or MSProject or Sharepoint can do the same - and to some degree that's true. But redmine/planio takes all of that to the next level, makes it super easy and configurable, and provides an end to end solution all the way from Senior management right down to day to day team members.
Ease of use