8.2 is coming next year as well which supposedly offers the ability to optionally MERGE the old and new interfaces.
Yes, you should upgrade to 8.1 but create a backup Image:
1. Create a backup IMAGE using Windows or Acronis True Image (or other) to a second drive
2. Go to the STORE link and see if the 8.1 update exists (if not you need to do all the Microsoft Updates)
3. Start the update.
I think the file was 3.5GB and took me two hours to download then a little while to install. I forget how long.
I use START8 anyway so I noticed absolutely no change visually.