Board Thread:General Wiki Discussion/@comment-5486221-20160803133231/@comment-5486221-20160825065630

Alien Force:


 * Kevin joined the team way too easily.
 * Overusing certain aliens, while neglecting the rest.
 * Taking away Vilgax's credibility while making him stronger (he can defeat the heroes of 10 worlds, but gets easily defeated by Diamondhead, who he broke the fingers of in the original series).
 * Poor tone shift from Season 2 to Season 3.
 * Ben's personality in Season 3.
 * Lack of an explanation as to why Ben removed the Omnitrix.

Ultimate Alien:


 * Neglecting the Ultimates.
 * Hardly giving us any explanation as to what the Ultimates actually are.
 * Half-hearted Season 3.
 * Rip-off of a theme song (I was really disappointed when hardly any original aliens returned).

In response to the posts above, while the two series brought back old villains, the new ones they did have were pretty good.