The attack speed affix has been reduced significantly on all items. The following list outlines all of the previous values and new values for each affix level. This should give you a rough idea of how much IAS you should expect to lose.
Weapons
Haste 1: Old: (2-3%) New: (2%)
Haste 2: Old: (4-5%) New: (2%)
Haste 3: Old: (6-7%) New: (2-3%)
Haste 4: Old: (8-9%) New: (2-3%)
Haste 5: Old: (10-11%) New: (3-4%)
Haste 6: Old: (12-13%) New: (3-4%)
Haste 7: Old: (14-15%) New: (5%)
Haste 8: Old: (16-17%) New: (6-7%)
Haste 9: Old: (18-19%) New: (8-9%)
Haste 10: Old: (20-25%) New: (10-11%)
Other Types (Rings, Amulet, Gloves, Legendaries)
Haste 1: Old: (2-3%) New: (2%)
Haste 2: Old: (4-5%) New: (2-3%)
Haste 3: Old: (6-7%) New: (3-4%)
Haste 4: Old: (8-9%) New: (3-4%)
Haste 5: Old: (10-11%) New: (4-5%)
Haste 6: Old: (12-13%) New: (5-6%)
Haste 7: Old: (14-15%) New: (6-7%)
Haste 8: Old: (16-17%) New: (8-9%)
Source - http://d3db.com/news/id/268-datamine...es-unofficial/