I have limited experience--my first batch will be ready to bottle in a couple weeks--but I too got a different amount of sugar than called for in the recipe. The guy at the store said it's because we're at a higher altitude--need a bit more sugar to make it right. For your first brew, I'd stick with what they're telling you, until you feel comfortable enough with the process to mess around with the recipe.
As for the finished product, more sugar when priming can lead to more CO2, more residual sugars, and more ABV. (Someone correct me if I'm wrong, but more sugar could also lead to a 'thicker' mouthfeel, right? If you don't want your lager to be more viscous, it might be best to leave it as they recommend.) Of course, the priming sugar isn't the only factor for any of those, so for a newcomer to the hobby it would be difficult to tell how it affected it, unless you ran a second batch by the letter and compared.