People keep mentioning Batman Begins as a successful film with mulitple villains, but there is only one MAIN villain, Ra's Al Ghul. The scarecrow and falcone are basically just working for him and recieve limited but enough screen time as a result.
The reason S3 didnt work was because there was 3 MAIN villains, which cannot be made to work. S4 needs to have 2 villains max for a few reasons:
1. Better character development, obviously...
2.Longer and more intense one on one battles, lets have a fight that can compare with the train scene!!
3. There arent enough good villains to have loads in each film, by 5 and 6 who will he be fighting....the spot??
Sadly its pretty likely that seeing as this movie made so much that Sony will have at least 3 villains for the next one for fear of losing box office, heres hoping they make a movie for critical not commercial success!!