  We investigate the continuum and emission line properties of 4576 SDSS
quasars as a function of their optical/UV SEDs. The optical/UV color
distribution of our sample is roughly Gaussian, but with a red tail; we
distinguish between 1) intrinsically blue (optically flat) quasars, 2)
intrinsically red (optically steep) quasars, and 3) the 273 (6%) of our quasars
whose continua are inconsistent with a single power-law and appear redder due
to SMC-like dust reddening rather than synchrotron emission. The color
distribution suggests that the population of moderately dust reddened
broad-line quasars is smaller than that of unobscured quasars, but we estimate
that a further 10% of the luminous quasar population is missing from the SDSS
sample because of dust extinction with E(B-V)<0.5. We also investigate the
emission and absorption line properties of these quasars as a function of color
with regard to Boroson & Green type eigenvectors. Intrinsically red (optically
steep) quasars tend to have narrower Balmer lines and weaker CIV, CIII], HeII
and 3000A bump emission as compared with bluer (optically flatter) quasars. The
change in strength of the 3000A bump appears to be dominated by the Balmer
continuum and not by FeII emission. The dust reddened quasars have even
narrower Balmer lines and weaker 3000A bumps, in addition to having
considerably larger equivalent widths of [OII] and [OIII] emission. The
fraction of broad absorption line quasars (BALQSOs) increases from ~3.4% for
the bluest quasars to perhaps as large as 20% for the dust reddened quasars,
but the intrinsic color distribution is affected by dust reddening. (abridged)
