Well, first seasons of Sci-Fi shows are often not that great.  But they tend to get better.  After the first season is over, then I will say if it is or isn't fully promising yet.  

In a nutshell, aliens from another system comes to Earth after their sun goes nova. While the Earth's governments debate on how to handle the crisis, their ships explode while in orbit and crash to the surface.

Some of the ships have Terraforming equipment onboard and change the landscape, plants, as well as animals to new and sometimes horrible creatures that now roam the Earth.

And now, 20-30 years later. Humans and as well as 7 different alien species now cohabit and intermingle on Earth. With the different views and culture trying to understand one another, hilarities are afoot and culture misunderstandings run wild in the city that used to be St Louis, MO. That is renamed Defiance...Oh yeah, Antarctica is now beachfront property if you can get there...