I recently signed up for the pro version of nitrous.io since they are phasing out the old version that I used for free. So far I am very pleased. Now you get isolated containers to work in with root access. I use the $15/month version that gives you 1G ram and 20G of disk space for a total of two containers. Since I only use nitrous.io for development, I found it easier just use one container (using the entire 1G ram) and cloning the git projects that I am working on.
Some of the things that I particularly like are:
The editor built into the web based IDE handles just about all programming languages and file types.
There is a separate app than can do two things: sync files between your laptop and your container and also forward ports so you can test run apps in the container and use your local web browser. If you don't want to forward ports, you can use their preview option that opens a new browser tab and lets you test in your browser without any port forwarding.
The battery on my laptops last longer if I do builds and test runs in the container. No (or less) fan noise :-)
It is easy to spin up a new container for experiments and just delete it.
When I am travelling, I don't have to load up a particular laptop with all of my projects - everything is in my cloud container so all I really need is a web browser.
Plays nicely with Heroku. I haven't tried it, but nitrous.io is also set up to play nicely with Google Cloud Services and Microsoft Azure.
With a little setup, you can SSH into your container from your phone, tablet, and laptops.
The nitrous.io web IDE reminds me of the Cider web IDE that I used internally at Google.
In general I think I save a fair amount of time having a container always available with my setup.
I tend to use my Mac and Windows 8.1 laptops more often that my Linux laptop, and even though I have SSH, git, IntelliJ, etc. set up on all of my laptops, always having a Linux development environment no matter what device I am on is a more consistent development experience.