13-episode seasons isn't really a creative decision. They're the norm (well, that or 12-episode seasons) on premium cable channels (like with Spartacus) and when a show like V only gets a a 13-episode season it's because networks usually only order thirteen episodes of a show and wait to order another nine episodes if the show does well. Only getting a 13-episode season on a regular network is a bad thing and rarely happens if a show does well. Of course, sometimes shows do get renewed for a second truncated season to give them another chance, but they usually end up canceled after that. See also: Dollhouse and Pushing Daisies.
Of course, in the case of Terra Nova, the episodes have an unusually long production time due to the special effects, so the fact that it had a short season may not mean anything. It doesn't seem all that popular, though.
Aaanyway, I've mostly heard bad things about this show, except that the season finale is supposed to be good/sort of okay.