My first Worldcon was quite the experience, given that it occurred in conjunction with the rise of the barking-mad puppy brigade trying to torpedo the Hugo awards. As a result, I was paying a bit more attention to the awards than otherwise I might have, instead of just roaming the convention and enjoying the experience.
Some impressions, though:
Fandom is an interesting intersection of two subcultures I already know: the tech conference culture and the gamer culture. I saw a lot of archetypes I knew, without seeing any of the individuals, which was really, really weird. I kept expecting to trip over PyCon buddies, but never did, and instead ended up talking to strangers a lot.
I was surprised and pleased to see the wide range of physical abilities that make up the fan culture. Accessibility took a front seat in the conference, and it's easy to see why as the range of physical capabilities on display was very, very broad.
A colleague of mine was manning a table offering pronoun badge ribbons which was a fascinating addition to the con. In general, despite the reputation of fandom for being prone to erasing or dismissing diversity, I saw a lot of inclusion on some fronts. I think that racially fandom is still very, very white, but on a lot of other fronts it's quite open.
The upshot of it was, I enjoyed the hell out of my first Worldcon. Navel-gazing aside, I mostly wandered the con, people-watched, and attended the many post-day parties. I'm exhausted but happy. I foresee making these a regular thing in lieu of PAX, as PAX may have become too big for me to properly enjoy.