Well, on the mandatory system that was in place since before it came up in Parliament in 2005, I'm aware of only one restaurant--Extreme Pita--that provides nutrition information, and it's not even on the menu; it's on a kind of separate menu.
For the vast majority of restaurants, you have to go to a website to find out the information. That turns a simple trip to a restaurant into a research project, if you want to get some useful information out of it.
There was an interesting study done by the Rudd institute in the United States. Some industrious grad students monitored about 4,000 people going into restaurants to see who among them looked for the nutrition information--at the brochures or the posters. Of the 4,300 or so, only six did, so it's an extremely low usage rate, and that's not going to lead to any kind of dietary changes.
A good study done by an economist at Stanford University showed that the mandatory system in New York City actually led to some pretty significant changes: a reduction of 14% in the calorie count for foods purchased at the Starbucks chain.