I have bought one, few months ago. It's been working great so far. Although I would recommend that you don't use it for personal use, Since the admins or the superadmins have access to your data. So you better either secure your data or put something on there which you are not much worried about losing. Have also seen someone selling unlimited GD with admin access, but don't know anything about it.
Rest make sure you don't keep pirated stuff or anything that will violate Google's ToS, and you should be good to go. Even you do make sure it is not public, you wouldn't want to get reported. Buy from a trusted seller with good reviews.
I would say it is good to have one. But I would keep a backup in an external HDD. GD is great for sharing big files with others or dumping huge files with little use. Definitely go ahead buy one according to your needs, but make sure you know what you are paying for.