Okay, not exactly fanservice, but fanservice can take different forms. There was no explanation of "the world between worlds", though it was obvious that she was in some kind of alternate place or dimension. But Jacen could hear them fighting, which was interesting, and it settled the question of whether or not it was just in her head. Anakin showed up for reasons unknown, and many are raving about how great he was, how much he looked and acted like the Anakin from the animated series (which of course was lost on anyone who never watched them).
Many are also saying "Well, this is basically Season Five of Rebels, what did you expect?" What I expected was a story that held together without having to know all the backstory, as we were promised and as I actually expected Filoni and company to pull off, given their track record. This is turning out not to be the case, and I'm starting to side with those who say that they're pretty lost without all the backstory. I know some of it, having watched some recaps prior to this series, but this is not the standalone story that it was promoted to be. It's clearly an extension of stories and characters that are well-established. You can't please everyone, I get it, but generally you try to aim for the largest audience, and that would be people who have not seen the animated shows, not the ones who have.