The Reapers are coming, but you knew that already
After the Lair of the Shadow Broker came out, it seemed Bioware's streak of delivering mediocre to decent DLC's for their games was over. After delivering rather bland releases for the first Mass Effect and okay-but-not-exceptional ones for Dragon Age, in came Shadow Broker and blew away everybody by being really awesome...and then it stopped. No more DLC but then news started appearing that what's supposedly the final DLC, "Arrival", was to come and now here we are, the mission that will get you hyped for Mass Effect 3. Well...it sort of does because the problem with Arrival isn't the fact that it doesn't advance the story since it does an admirable job of it, it's just not exceptional either, especially for something directly about the Reapers.
After downloading the DLC, you receive a message from Admiral Hackett (and his face too!) concerning the capture of Dr. Amanda Kenson, a researcher with possible information about the incoming Reaper invasion. So Shepard is sent alone to try to rescue the doctor and in doing so, finds out about the incoming Reapers and the plan to stop them. And that's basically the story in a nutshell because going any further would spoil what goes on but the main issue with Arrival isn't so much about how it advances the story but rather the actual storytelling of it. It's just a very bland DLC, there's a pseudo-stealth sequence (if you're achievement hunting), a part where you must survive a bunch of enemies (for another achievement) and some linear corridor shooting by yourself before you get to the end. Unlike Shadow Broker which had some moodier atmosphere, a car chase, 2 boss fights and a stunning 2nd act on a visual front, Arrival doesn't do anything to make it stand out.
Not to mention the DLC itself just feels not necessarily insubstantial but like it didn't even need to be DLC. A visual comic released online would've gotten the job done but there's nothing really worthwhile other than 2 cool conversations near the end. There's no new squadmates, no weapons, and the other upgrades are just stuff you already have (like Heavy Ammo). Unlike Kasumi which added a great new SMG, the only thing to get out of this release is the story which at the end is summed up as "the Reapers are still coming". Great, just like if I never bought the DLC.
There was one simple thing that would determine whether or not I'd buy Arrival: if I had everything else. And sure enough from Kasumi to Overlord and Shadow Broker, not getting Arrival just doesn't make sense but this DLC feels like a wasted opportunity. Instead of getting one pumped for the third installment, you leave Arrival the same as you came in: pumped for Mass Effect 3 anyway regardless and this doesn't make that wait any bigger.