That's not $0.99 a month, mind you, but $0.99 in total for your first 120 days or so playing tunes from Amazon's massive library without ads, interruptions, or limits of any sort on everything from handsets to tablets, computers, Fire TV streaming devices, and of course, Echo smart speakers and smart displays. There are tens of millions of tracks you can choose from (so, no, not just holiday songs), as well as thousands of curated playlists and stations, all of which are accessible both on and offline.
Basically, this is Amazon's answer and direct rival to the market-leading Spotify and Apple Music platforms, with the need to draw in the crowds and attract subscribers from said industry trendsetters the main reason why great deals like this have gotten incredibly easy to come by. You might remember an identical promotion taking place just last summer, while students don't even need a special occasion to pay $0.99 for their unlimited music streaming rights month after month nowadays.
All other users can sign up for the newest limited-time Amazon Music Unlimited promo by January 6, 2020 as long as you're not already subscribed and have never tried out this particular service. If you meet those requirements, you may want to note you'll be automatically charged the standard $9.99 monthly fee ($7.99 for Prime members) immediately after these first four months will end unless you cancel your subscription.
As far as we can tell, there are no other special conditions or strings attached, so if you're new to Amazon Music Unlimited and want to give a top Apple Music and Spotify alternative a whirl ahead of the holidays, this seems like a no-brainer deal.