As others said it is in test form,you can also try it.
But what is the difficulty of using the current UI of bitcointalk? It seems easy and comfortable with current design than sites with more animations or whatever you consider as fresh design.
It's a nightmare for mobile users. No mobile responsiveness so you gotta zoom in everytime you refresh the page.
I don't really notice the problem you are facing right now. Even if the website doesn't adjust to mobile and desktop view of the browser I still feel comfortable using the current Bitcointalk's U.I.. Yes you can't add links, quote messages, and edit your post quickly but the basics of posting and replying is still bearable on my end. It may be because you have an outdated mobile phone or have a small screen that is why you don't think BCT's current U.I. is not good being viewed with a phone.
P.S.
I'm posting this using my phone right now and I don't see any problems with it.