There were some cute and funny parts (like lawful-Piranas losing their car and the roots chemical plant), but I agree it did feel a bit rushed. Now the question is if Gheist supposedly rescued Sigmund in the previous story yet he's in the mirror world, does that mean they got the mirror Sigmund instead or do they only just know the location of him?
No doubt a sequel will be in the works.
So, Sigmund is still alive (or more so) in the reverse universe. Either the robot version of him is the real Sigmund and we just saw Bizarro Sigmund or...the robot version is a cloned copy and the real Sigmund from Clint City managed to go into the other dimension.
I like the second theory because it would make the story more interesting.
The montana are full of good hearts (as in charaty), and although Sigmund Cr left and Mini mund took his place, he's the leader of the dark sentinel (dispite the fact that vryer is in prison, and the rest of the GHEIST are in the nursing deparment of the Rescue hospital.