There were a lot of factors that made II fail so much. Mainly they axed off most of the original team, the creators left, and then they butchered the entire script. Also, they put the guy in charge of the game maps as the director. THE FUCKING DIRECTOR. By the time III was made, it was essentially Episode 2.5.
But yes, there was no point in playing II if you hadn't played the first. Just completely turns you away from an otherwise good series.