The whole story of the Omega DLC is that Aria T'loak wants to reclaim Omega back from Cerberus after they took over Omega. The whole problem with the story is that it pretty much doesn't affect anything in the main game. Once the story is over there will not be a single mention from any of your squad and straight after the mission is over Aria will be back at the citadel like nothing happened a few minutes ago. The whole concept and idea of a Omega DLC story was very cool but it didn't seem to come together well. I was thinking maybe it would have been better to shorten the mission down and used as a main story mission so maybe we could have had some changes after the mission was over.
Non of your squad can come on this mission probably because of cost reasons and bringing back all the voice actors from ME3 will come at a cost which is something Bioware wanted to avoid. The storyline reason given is Aria only wanted Shepard to come on the mission and no one else which Shepard agreed too. This is another reason why it would have been better as a main game mission because the voice actors would have been there to voice their characters and we would be able to use them in the mission and also they could offer some opinions after the mission is over.
The gameplay in this mission is really just run and shoot for a few hours which can get really boring after the first hour or so. Omega was really missing the exploration that was in the previous Leviathan DLC. The whole DLC just felt repetitive and linear which was a real shame. In the mission you will meet Nyreen who is a biotic Turian who knows Aria.Shepard and Aria will team up with Nyreen through the mission but don't expect Nyreen to be with you all the time as most of the mission is just Shepard and Aria. The big downside is that the two were really cool to have as squad mates but you can't ever use them again! Aria and Nyreen won't be joining your squad when the mission is over which was a missed opportunity by Bioware to have some new Squadmates (Interesting ones too)
Here is what you can expect to not receive in the Omega DLC. You won't be able to free roam around Omega after the DLC is finished. This was a HUGE disappointment for me I thought we was going to be able to roam around Omega and visit the Afterlife club to see Aria sit on her chair again like in Mass Effect 2 but that won't be happening like I mentioned before she will stay at the Purgatory bar at the Citadel like nothing happened. Don't expect any new squadmates added to the team, current squadmates mentioning the mission or even talking about your disappearance and it all causes it to just feel the same once it's all over and the DLC doesn't come cheap as well it is 1200 Microsoft points for this DLC.
The Final Verdict
The Mass Effect 3 Omega DLC was a massive let down and is up there with some of the worst DLC missions in the Mass Effect trilogy. Sure it was cool to play the mission with new squadmates but after that they are gone and never to played as again (Unless you replay the mission of course) like I mentioned a few times it feels like nothing changed after finishing it. Even the mission its self was pretty boring and featured tons of shooting this and that and no where near enough exploration. Bioware proved they could still do good DLC for Mass Effect games and hopefully if they make any more DLC missions that we get some more of the same quality as The Shadow Broker in ME2 and DLC that will actually impact the main game like new discussions with squad members and new squad members. I don't recommend you get this DLC now and I think you should wait until it is down to the 560 MS points mark.
+Cool to have the new squadmates in the mission
+New enemies and powers
-Nothing changes/Rewarded with nothing new
-Mission gets boring quick