The pre-WMAP CMB angular power spectrum assembled from multiple experiments is very well fit by a six-parameter model. Of these six parameters, the vacuum energy density V and the redshift of reionization zri are still poorly determined from CMB data alone. However, the well-determined parameters either match independent determinations or the expectations from inflation:
The angular power spectrum of the CMB can be computed using well-understood physics and linear perturbation theory. The current data set agrees with the predictions of inflation happening less than 1 picosecond after the Big Bang, the observations of light isotope abundances from the first three minutes after the Big Bang, and the observations of LSS in the current Universe. The inflationary scenario and the hot Big Bang model appear to be solidly based on confirmed quantitative predictions.
The greatly improved CMB data expected from WMAP, and later Planck, should dramatically improve our knowledge of the Universe.