The problem with frontier is that it drags its plot out for too many episodes, there's just not enough interesting in the show to carry the hopelessly senseless story.
If there is one thing frontier suffers from it's being generic and trying to imitate (poorly) what made the original macross series so popular.
Then there is Japans obsession with shoe-horning songs of j-pop stars into space opera. In frontier it just doesn't fit well at all with how they implemented it. The problem is that they do more then just have a singing pop star in the show but use the pop stars voice as a plot device to defeat the bad guys. I'm sorry to say it but this is just amateur level storytelling here. The whole plot is simple and comes off completely campy towards the end of the series making you feel like you wasted your time.
Another problem is that the characters are just not believable. For instance the main character and his love interest is written poorly and exists on a level of uninteresting blandness that I haven't seen in a long time.
Another problem is the characters have no depth and so you can't really identify with them at all, so you never feel in any way immersed or connected to the characters.
The problem with macross frontier is that it is corporate soul-less remake with no genuine heart and soul. The originals had way more soul then frontier can ever hope to have.
