I see that it's on sale for $5 and I might as well get some practice before BF1 comes out. However, if it's dead I'd rather save my money.

More populated than Hardline and Battlefront EA

Premium is probably worth a purchase too if you get the chance [well, dependant on if you're getting BF1]. You can still find servers running dlc maps.

Also, there are three free map dlcs; night, communuty and legacy operations. They add 3 new maps and are completely free.

The biggest problem you'll have is finding a server with enough spaces.