Love CFD's personally, great for leverage and entering with greater position size with a drop of a hat. Love playing with $500 and being exposed to $5k parcels.
As another poster said above, need to watch the gaps.
CMC Markets (and a I believe now virtually every platform) now automatically closes your position of your account reaches 50% or less of your margin (from memory) - so potentially no need to worry about losing more then you started with.
A good CFD trade (IMO ONLY) was FGE when it re-opened @ around 30 cents, I capitalised on it on the way up as I'm sure did many others.