I see people wrongly judging La Brea based on the idea that it's sci-fi. This is not a sci-fi show. It's a fantasy show similar to the type of fantasy that Lost was (Lost was NOT sci-fi). Not LotR elfland magical fantasy (so far) but still fantasy. If you have a hard time suspending your disbelief or often find yourself shouting at the TV screen/monitor "that wouldn't happen!" you probably won't like this show.
People fall through a sinkhole and end up traveling back in time or to a parallel dimension after passing through some sort of rift or portal. It definitely feels kinda like Lost with survivors banding together in a hostile world trying to survive. I don't mind that because I liked Lost. Prehistoric animals, psychic visions, aurora borealis looking sky rifts, disaster CGI effects... it's a pretty show, well made with good cinematography and decent pacing. The acting is on the meh side and I'm not particularly drawn towards any of the characters. As others have said, the writing is somewhat lacking so far with very stereotypical character archetypes and bland dialog.
Nothing is egregiously bad (other than one of the characters in the opening suggesting they move back to San Bernardino) or mind-blowingly amazing, but for a pilot it's not that bad which is why I give it a solid three stars.