We are currently using it for development, however the last release was Service Bus 1.1 over two years ago.
Should Service Bus for Windows Server be avoided?
It's kinda dead.
Mainstream support ended 1/9/2018. Extended support will end 1/10/2023.
So if you are running the service bus and do want to keep running your bus on premise and not in a cloud you have a little less 4 years from now to find and deploy a replacement.
Edit: It is officially dead. Microsoft "will not provide an immediate successor for the standalone Service Bus for Windows Server 1.1 product" and it "and will go out of mainstream support on January 9, 2018".
You may want to monitor this Stack Overflow Question (which points to this UserVoice idea) for updates on it being brought to Azure Stack so it can be used on-premise. The latest update from Microsoft was from Sept. 30, 2018 - "Thanks for your feedback. We are pleased to inform you that we are bringing Event Hubs to Azure Stack. We announced Private Preview at Ignite 2018... Service Bus will follow next." As of Dec 2019, Event Hubs is still listed as "IN DEVELOPMENT" on the Azure Stack key capabilities site.
Original answer (Aug 4 '16):
The short answer: Service Bus for Windows Server does have a future as part of Azure Stack but it is not going to be free and will not happen this year (2016).
Apparently the roadmap was announced on May 12 at Integrate 2016 during Clemens Vasters's Service Bus – Roadmap, What’s next? talk. You can listen to the announcements related to Service Bus at about 40:35.
Interesting quotes from the video:
Thanks to user Arunkumar BizTalk360 for pointing us in the right direction in this Microsoft Azure thread
It is not dead. It is a fully supported add-on to Windows Server 2012 R2. A roadmap for the way forwward will be announced later this year.
Turns out, it is dead now....
https://azure.microsoft.com/en-us/blog/collaboration-and-federation-azure-service-bus-messaging-on-premises-futures/
As a consequence, we are announcing today that we will not provide an immediate successor for the standalone Service Bus for Windows Server 1.1 product. Service Bus for Windows Server 1.1 was shipped as a free download that could be installed inside and outside of the Azure Stack precursor Azure Pack. The product is available as a free download and will go out of mainstream support on January 9, 2018, following the regular Microsoft lifecycle policy as published at the initial product release.