The only thing I've noticed (I got gifted a month a few weeks back, I've got 4 days left) is that there are more subs on my front page (which is kind of annoying since I'm not subscribed to that many, so they're pretty much the same ones all day long) and there's a "myrandom" button next to "random". There's also the "lounge" which I went to maybe once to see what it was all about. It's nothing super special. No ads, of course, but if you use adblock it's the same.

There is an upside, though. If you use Android, the Reddit is Fun app goes ad-free for free if you have gold. I'm not sure if they continually monitor it or if it just activates ad-free mode forever. There are a couple other companies that offer similar/different perks, but that's the only one that sticks out.