I must say that the idea of paper trading does not appeal to me as people have said - there are no emotions as nothing is at stake.
Being new to trading index futures I have started trading in the smallest amounts available - via finspreads. This amount is 1penny per point which I find does elicit strong emotional responses - accepting that they will not be as strong emotions if it was £10 a point! I have found this real, real-time, small risk, learning invaluable. And because the values I'm trading are so small, I can't use limits or stops, which means I have to be extra disciplined to get out at my stop (especially) or at my target - hence I have to use market orders always.
Not having used a simulator I can't comment on their value, but I suspect that it suffers the same fundemental limitation of paper trading - ie. there is no risk, hence no emotions, its not very useful when it comes to trading the market. Having said that, I can see it may be useful in learning about placing the different order types etc.
Mutters