Not only newbie can profit from forex demo account. Both newbie and a professional forex trader can learn how to actually use the trading platform of the selected broker via demo accounts. It is never a good idea to start trading for real money without knowing which button to press to get the charts, where to see the currency rates, how to track your account history, how to execute, make or close the trade. The last thing you want to do is to go over a long list of Questions-Answers or franticly wait for online support to help you with a simple trading task. Forex market is fast – it requires a fast reaction from your part. If you don't know how to operate your trading platform, you are simply screwed. So, yeah, I am very pro demo account. Practice everything you can possibly think of with your forex demo account before you even consider a real live account.
Another beautiful thing about demo account is that you can make mistakes and watch what happens!! You can analyze your actions, set ups and carts without freaking out about money being lost. I would even suggest making mistakes with demo accounts and taking losses! It will teach you about risk management strategies which are crucial in forex trading.
The bottom line is that forex demo accounts are free of charge and it didn't hurt anyone to open one yet!!