Free to experience until January the 2nd IIRC. It's about $80 dollars or so normally so even it's worth having a go even if you don't take to it.
The Tomcat is an absolute beast, though, so be prepared to be reading an instruction manual just to play a game if you want to go all out.
Also, to anyone who goes on DCS multiplayer for the first time: IFF IFF IFF.