The standard Fed ships look pretty darn good, but the Fed concept ship and the Battlebird aren't great. Actually, the Battlebird could be good if they did a lesser slope to the rear hull. It just curves far too much and gives the bird ass an atrophied look. It looks completely off scale with the rest of the ship.
Their Sabre looks a little... flat. Not enough... something. I dunno, it just looks off somehow and I cannot verbalise it. Maybe too plastic-y looking, to shiny&rounded.