Dead on...
I'm going to post a longer review over on horriblenight.com, but in short, "The Arrival" should have been pre-titled "Dead on..." For $7, it was disappointingly short, had quite a few mechanical glitches and if it represents what I have to look forward to in ME3, I went from being a confident fan boy knowing I'm going to pre-order that with all of the bells and whistles to a very nervous fan boy thinking about shooting BioWare a message and saying, "Um, guys...you were kidding with "The Arrival," right? ME3's going to be way better than that. Right? Guys?"
Just because they got Lance Henrikson to reprise as Admiral Hackett and actually show up, separating you from your team for the entire mission and swarming you with either batarians or alliance soldiers for most of the ~2 hours wasn't what I had in mind when I was pee-my-pants excited for this bridge between 2 & 3. Considering how well done Lair of the Shadow Broker was (for only $3 more, I might add), how long it was, and the post-play impact of the Shadow Broker base (oops. spoiler alert. It came out 6 months ago, get with the program), there's pretty much no excuse for The Arrival.