I don't really have nostalgia, per say, because I grew up with Bionicle, but don't get me wrong, I can totally get behind HF Appreciation!
Mostly because there's a lot of potential in the idea, and I like it when people take it and make MOCs and stories that are far better than anything LEGO could crank out.
In terms of actual nostalgia, it's mostly initial heartbreak, then me going, "Okay, I can try this out" then, "I hope this keeps getting better" then, "What are you doing, LEGO?", and then "Yea...no."
But like I said, I think there was so much potential in the line. I'd rather have the ideas put into Bionicle, but if there was no G2 I could get behind a better HF.
Also, I prefer HF's original villains, so much personality even if they were one-sided a bit!