  The Next Generation Deep Extragalactic Exploratory Public (NGDEEP) survey
program was designed specifically to include Near Infrared Slitless
Spectroscopic observations (NGDEEP-NISS) to detect multiple emission lines in
as many galaxies as possible and across a wide redshift range using the Near
Infrared Imager and Slitless Spectrograph (NIRISS). We present early results
obtained from the the first set of observations (Epoch 1, 50$\%$ of the
allocated orbits) of this program (NGDEEP-NISS1). Using a set of independently
developed calibration files designed to deal with a complex combination of
overlapping spectra, multiple position angles, and multiple cross filters and
grisms, in conjunction with a robust and proven algorithm for quantifying
contamination from overlapping dispersed spectra, NGDEEP-NISS1 has achieved a
3$\sigma$ sensitivity limit of 2 $\times$ 10$^{-18}$ erg/s/cm$^2$. We
demonstrate the power of deep wide field slitless spectroscopy (WFSS) to
characterize the star-formation rates, and metallicity ([OIII]/H$\beta$), and
dust content, of galaxies at $1<z<3.5$. The latter showing intriguing initial
results on the applicability and assumptions made regarding the use of Case B
recombination.
  Further, we identify the presence of active galactic nuclei (AGN) and infer
the mass of their supermassive black holes (SMBHs) using broadened restframe
MgII and H$\beta$ emission lines. The spectroscopic results are then compared
with the physical properties of galaxies extrapolated from fitting spectral
energy distribution (SED) models to photometry alone. The results clearly
demonstrate the unique power and efficiency of WFSS at near-infrared
wavelengths over other methods to determine the properties of galaxies across a
broad range of redshifts.
