This is partially correct. Yes Windu got played, but GL has stated that Windu won the Lightsaber duel. Which means that Windu is a better duelist than Sidious. Now if Sidious did use his full power, Windu wouldn't have a chance.

Simplified:

Windu > Sidious - Lightsaber

Sidious > Windu - Force Power

It's only partly correct. If you want me to go in-depth over it, say so.

I just realized something.

1. We know that Mace is a better duelist then Sidious.

2. We know that Qui-gon, Dooku, and Yoda where all equals in lightsaber combat with Mace at one time.

If this is so, I guess Sidious isn't so special with a lightsaber (obviously he makes up with this in force beastliness). Perhaps I'm thinking through this incorrectly, but does this mean that Dooku is a better duelist then Sidious? That just seems crazy to me.