Being a vlogger is good in case you enjoy it and also make some money from it. You can post whatever you want, but the question is will your audience be interested in it? Thus, it is important to choose a topic that addresses a particular issue for a particular audience. Or a topic that can be of a general interest, like traveling, cars, lifestyle, fitness, etc. If you manage to grow a big audience, YouTube will start paying you and also some companies will be interested in giving you ads as you will be considered a video influencer. 

I can't see any disadvantage of vlogging, because people consider it as a hobby, and hobbies are always fun. So, think about something fun that you enjoy doing (if you really want and feel like vlogging).