I really enjoyed it, it hit alot of the right marks for a Pilot.
Many SciFi shows, spend so long building up their characters and their Universe elements, and today's audience gets quickly bored and moves on, and the show is cancelled before it gets a chance to really hit it's stride.
I respect the decision TNT made on this, to start it after the Aliens had already invaded and were in control. So, you're already in the heart of the action from the first frame. Truth be told, I think I might've liked a little build up, or at least a narrative over the opening credits sequence, something like "6 Months ago, they came. Why we don't know yet, but, they..." However, I think it was a wise decision to start the series in the midst of it, might be a really good way not to bleed viewers quickly.
At first, I was a bit nervous, when they kept advertising Noah Wyle as the Lead, thinking, although, I like him alot, I don't really think he's capable of carrying an Action Series as it's lead, maybe a Sitcom as a Cliff Huxtable type father. Turns out, it's a true ensemble cast, without a single lead, so that's good.
There's an Anti-Hero in the vein of Sawyer from LOST, or Baltar from NuBSG or Dr. Rush from SGU. Very well cast, I was very impressed with Colin Cunningham's portrayal of this character, he was a favorite for me. Also very impressive is the Grizzled Military Leader, very reminiscint of Sol Tighe from NuBSG, but, in control, not the really fracked up, lacking confidence drunk Tigh was most of the time on NuBSG.
Lots of realism with the unkempt streets and landscapes, real problems like a young boy whose feelings are hurt because military manuevers will screw over his birthday.
I'll definitely continue watching.