You can play for free, but you can NEVER finish it.You have to buy from the cash shop in order to have end game gear.Nobody will have you in their party if you do not have it. They don't want to see you dying all the time.
Not only that but this company violates it's own TOS and allows players to harass other players. I got banned for reporting a player harassing me. Read more here, if you like.
The moderators should remove this entire thread from the forums, this game has not been free for a long time now.