Why complicated you ask? It's not the controls or the challenges... It's playing career mode! Having to do a different set of trick challenges and finding the extra boards in different places simply because of the style of said pro skater was a bad idea. Other than that the game is cool, nice soundtrack, nice graphics for the time, all that stuff.
The only issue is the flat ground tricks which were new at the time, too complicated to do a trick and it made you lose your balance too easily. Thankfully this was refined in the later THPS games (or THPSUGAWPG if you prefer).