If you can fit it into your schedule and budget, GO! I've been to the previous two and my tickets for DC were bought and hotel was booked before I left Denver.
The opportunity to talk to and learn from the people that make this hobby possible is something you don't want to miss out on. It's awesome to go sit down with Scott Fellman and discuss his most recent articles and then go pick Austin Lefevre's brain about a coral you're having trouble keeping alive. It's a great time talking to and getting to know all of the vendors, but it is absolutely mind blowing to listen to, and converse with the people who literally make this hobby possible and expand man kinds knowledge of the oceans and what's in it. The guys who actually risked their lives to discover, classify, and collect the animals we keep in our tanks. Having Richard Pyle narrate his unedited dive footage of his search for the Coelacanth was a once in a lifetime (and hilarious) experience. Being in the room when Rufus Kimura announced that the Masked Angel pair he collected bred in Karen Brittain's lab was incredible. There are hundreds of conversations and experiences I've had in only 6 days of MACNA that I could not possibly describe with enough enthusiasm. Your knowledge of the hobby will grow exponentially no matter how long you've been in the hobby.
Besides learning stuff and buying things, there's a lot to do. The banquet, drinking, raffles, parties, host city, and drinking is always a lot of fun and a bit controversial at times (you'd understand if you went). My girlfriend and I thoroughly enjoy the experience and count down the days until the next one. 183 days BTW.
You really do owe it to yourself, and the animals that you care for, to go to at least one MACNA. You wont regret it.