On the length: I don't think Goranger sustains itself as well as the original Kamen Rider, which is even longer, but that also has a nice clean divide between 52-53 so you can virtually watch it as 2 seperate series, Season 1 & 2 in a sense (well, you can watch it as about 4 seperate series if you really break it down.) It has enough thematic shift to it along the way, which Goranger really didn't have to support the running time.
And the monsters: A couple were pretty cool (I like the Gasmask one with his amazingly complex hat) but once again, Kamen Rider's blew them out of the water. I personally don't think Sentai really had monsters that I would say top what Rider was doing until the 80's, where there were some great designs coming out on a weekly basis.
Also, I think having unmasked actors for the major villains helps out, whereas the Goranger ones felt like "Monsters of the week who got to hang around a bit longer".
But that said, Goranger is definitely a fun one to see because it's the original, and a lot of the groundwork for later series is there. Although I think Battle Fever actually rings a bit closer to what we still have today because of the robot, which for better or worse is a profoundly important addition to Sentai. But Goranger's importance can't be denied, and I think there's plenty to enjoy in it. Also: Miyauchi in what I think is like a proto-Hayakawa role = awesome.