If you ask long time Wondercon goers to describe what it's like, a common descriptor is "The laid-back brother of Comic Con", and now if you were to ask me to describe it, I would say something very similar. This convention is much more relaxed, and the fact that you can buy tickets the day of the event is evidence of that.
The thing I loved the most about Wondercon is the fact that you can easily see everything you want without having to wait in much of a line. Having to wait in huge lines is one of the largest complaints about big conventions such as SDCC, and I can tell you that this is not the case with Wondercon. I was able to see the Adventure Time panel, DC Comics All Access panel, The Tournament of Nerds, and the Masquearade with out having to get in line more than a half hour in advance. To tell you the truth, I probably could have arrived at show time and I still would have found a seat somewhere in the back. This was mind blowing to me! I'm so used to having to pick and choose my panels that the fact that I was able to see everything I wanted to was so refreshing.
Another great aspect of Wondercon is that the exhibit hall is not too crowded. There is still a ton of people in the room, but there is plenty of space for you to walk around as you please without having to worry about bumping and grinding with your fellow con-goers. This not only makes things more comfortable but it also makes it easier to see all the booths and talk to the exhibitors. Getting to view the entire exhibit hall without fighting the mob was a nice experience.
Something I was unsure of was whether or not a smaller convention like Wondercon would be able to attract big panels and celebrities. But that's the thing, I'm not entirely sure you can call Wondercon small anymore, because over the past few years its attendance and "Hollywood Factor" has been steadily growing. Some of the big name panels that were at this years event were The Amazing Spiderman, Adventure Time, Abraham Lincoln: Vampire Hunter, and many more.
Wondercon 2012 turned out to be a near perfect convention experience for me. While the atmosphere is a lot different from what I am used to, it definitely isn't a bad thing. I actually think that it makes it better in its own way. The only downfall to my day was the fact that it was storming pretty hard outside, but Comic Con International doesn't have the power to control the weather (at least yet). I completely recommend that you check out Wondercon regardless of what city it's in!
-Mitch