kimchoson Progress is definitely being made almost every day. You can track it all yourself by checking out the milestones on GitHub. Just because you cannot see progress doesn't mean it isn't happening. ?
And don't rely on third parties for information either. Just like magazine articles and newspaper reports; they're the opinions and assumptions of the author at the time. If you see it announced by a developer or other Flarum staff member, then take that as gospel.
To answer your question on whether Flarum is worth it, well, my question to you is why wouldn't it be?
Yes it is new forum software to hit the market and there are many others out there that are already well established but different software suits different forum owners and administrators. Choose a forum software based on what you want to get out of it and whether it serves your purpose or meets your audience. Extension updates and new releases are currently on hold until beta.8 is released but once it launches you will have access to a vast array of them to improve what is already an awesome bit of kit. You can check out what our members have created in the Showcase your Flarum! discussion for some influence or if you need some reassurance. Some people are quite creative in getting Flarum to work the way they want it to.
Flarum is here to stay and won't be a project that is simply abandoned. There are some very smart individuals who are working together to bring you some powerful forum software that can be moulded to suit any type of community or project. Try it and see for yourself. Only then will you know whether Flarum is the right fit for you.