Hello SV,
From the Help: "Spline interpolates a raster surface from points using a two-dimensional minimum curvature spline technique. The resulting smooth surface passes exactly through the input points."
Looking at the graphic below suggest that the Spline in orange might create artificially high and low points in the DEM. A tin usually creates more of a triangle effect with a DEM that is shown in Red below.
I would suggest trying to use the Topo to Raster which interpolates a hydrologically correct raster surface from point, line, and polygon data. ArcGIS Help 10.1
Thanks,
Arthur Crawford