Roy Thomas has a habit of being really wordy with his stories and the first few issues of the Invaders lives up to those wordy and kind of boring trends.
The opening arcs are against stock silver-agey guys like Brain Drain and a bunch of aliens pretending to be Germanic gods. Nothing too exciting happens for awhile as Thomas goes through all the normal reintroductions for the core cast of Captain America, Namor, Human Torch, Toro, and Bucky. Thomas does immediately establishes a fun rapport between the senior members of the team. Namor calls the Torch "firebug," and the Torch calls Namor "water rat," clearly setting up their relationship. Namor is a heckuva lot more chatty than I remember him being and while he still hates surface men, he is also a lot more willing to talk smack than I'm used to. Another great bit with Namor is how often he makes veiled threats that he will turn on his teammates after the Nazis are defeated. He's not the greatest ally.
Things pick up when the Red Skull kidnaps and brainwashes the core team, leaving only the "worthless" Bucky behind. The story spins out into two fun issues of Marvel Premiere, introducing the Liberty Legion. The Legion is filled with luminaries like Blue Diamond, Red Raven, Miss America, the Whizzer, the Patriot, the Thin Man, and Jack Frost. Mixing all those guys together with Bucky and putting them up against the heavy hitters was a great idea, and the 7 on 3 fight is almost fair.
The closing story was the best of the trade, with the Invaders adding Union Jack to their lineup as they go up against Baron Blood. This was a good little story with lots of trickery from the Baron making this a closer matchup than I expected.
Frank Robbins' art was ok. He has a habit of doing odd faces and eyeballs, but for the most part everything looked ok.