Does unlocking GWEN change the other campaigns?

I just want to know if unlocking travel to GWEN, changes anything in the Prophesies campaign storyline or landscape.

I have not finished Prophesies yet but still might venture forth into GWEN with my characters and don’t want to change things that I have not yet seen or done in the former part of the Prophesies campaign, especially if it's something that makes it so that I can't go back and do them later. I don't mind if the story is out of order. I just don't want to miss anything or change something that I haven't done because of venturing forth into the latter part of the story.

Except for some holes in the ground near Lion's Arch, Kaineng Center and Kamadan, the landscape nor the storyline of the three prior campaigns changes drastically.

Ok. This is good news. Thanks a lot for informing me, RSGashapon.