I don't know about linux support, but they have native apps. This is much better than having an extra tab open all the time. As for your other concerns, you have listed a bunch of technologies that "already [do] that." Sure, there are plenty of them, but it's nice to have everything together.
Yes, as jscheel points out the native apps are far superior to the in browser option. We also link it into our production services such as pivotal, circleCI, etc to send notifications for build failures of deliverables. It's definitely a service that gets better the more you integrate it with your workflow. One stop shop and ease of use has also been a big selling point for my team
