This link contains our analysis of NASADEM vs SRTM across North America. We used 252 million extremely accurate IceSat-2 terrain height benchmarks for the comparison. The analysis also includes AW3D30 and ASTER DEMs for good measure.
This link is our second analysis of NASADEM across Australia and New Zealand.
NASA also publishes an ellipsoidal height dataset which improves accuracy a wee bit, which can be helpful if you're using bicubic interpolation. It has voids which are easy to correct. Note: its heights are not relative to sea level, and are different than what Google Earth and most other mapping products provide.
In short, NASADEM is a little better than SRTM in forests (less bias), short vegetation, wetland and urban areas, and a bit worse in barren areas and open water. NASADEM is even better in Australia, too. Also take a look at AW3D30 v3.1.