Not nearly as much in this DLC as I would have liked for $15. However, I have a feeling things may play out differently when I do a replay after class, which would explain the massive file size. Still not sure if the content justifies the price of admission.
Visually, you get to see much more of a sense of scale for Omega here than you ever did in ME2. I thought the combat was more interesting and fun than Leviathan. It took me about 3 1/2 hours to complete on Hardcore, so it's definitely not as lengthy as I'd have liked. However, it *felt* like longer than that, so take that as you will.
Grand question: is it worth $15? No. Unless you are DYING for more Aria content, in which case, go ahead. Or if you wanna splurge. It's definitely not a good value. For that price, I wanted more interaction with both Aria and Nyreen, more details on Aria's past, romance stuff, and a hub that I could visit after the mission was over, among other things. Considering what Awakenings was like for that price...yeah. Omega is nowhere in the ballpark of Awakenings. Not to mention Aria's grand speech was so glitched out I was laughing more than inspired.
All that said, though, I can't say I was disappointed per se. It was fun to go and kick ass with Aria, and like I said, the combat was fun (unlike Leviathan, where I wanted to poke my eyes out at the repetitiveness) and you're basically going full tilt from the time you land to the end.