An air taxi First Officer failed to see the 1;500 FT initial altitude constraint on the TEB RUUDY TWO RNAV departure and climbed to 2;000 FT; at which time ATC advised them of their error and issued a new clearance.

Narrative

As pilot flying I picked up the IFR clearance and reviewed the assigned SID (RUUDY 2) alone; while the pilot not flying completed a preflight walk around. Ambient lighting was dim and I was in a hurry while I looked over the SID chart. I failed to notice the 1;500 FT altitude restriction at WENTZ intersection. Instead I noticed and focused exclusively upon the 2;000 FT altitude at TASCA intersection. During taxi; I briefed the departure as I understood it - takeoff [and] climb to a 2;000 FT for our initial level-off. The pilot not flying did not query my briefing or altitude. He had only briefly glanced at the SID chart and trusted my briefing. After takeoff; I followed noise abatement and SID procedures; except for leveling at 1;500 FT until WENTZ; instead climbing to 2;000 FT. When the pilot not flying checked in with New York Departure; he stated our altitude of 2;000 FT. New York Departure then informed us that we were 'supposed to remain at 1;500 FT until WENTZ for your information; but you're okay. Turn left heading 240 and climb to 4;000 FT.' I was taken by surprise and confused because I was confident in my (incorrect) pre-departure briefing. Upon reaching cruise altitude we reviewed the departure and noticed the 1;500 FT restriction at WENTZ. Realizing the error in my briefing and the potential violation of altitude margins was a terrible feeling! The only explanation I can offer is human error in the form of omission while conducting a rushed review of the charted SID. The pilot not flying did not conduct a thorough and independent review of the SID chart; so he did not notice my error. In the future we will slowly and carefully review our SID charts both before starting engines and while conducting our pre-takeoff brief while taxiing. Although the plan view portion of the SID chart [is ok]; the textual description of the initial climb is difficult to read in the dusk while hurrying. Both factors (environmental and psychological) are correctable and this mistake should not occur again. We appreciated the New York Departure Controller's 'constructive criticism' and helpful attitude.