When companies bring out same-size sensors with an increased pixel count, one hopes that there has been some technological improvement so that the smaller pixel has equal or similar performance to the larger pixel of the previous generation, so that there is no loss in quality in any respect when the larger file is downsampled for comparison purposes.
To have the benefits of increased resolution with no downside such as increased noise, is a very worthwhile improvement.
It so happens that DXOMark have now released their test results for the D3200. Comparing those results with the D7000, it seems that the D3200 is a backward step regarding DR.
SNR at 18%, Tonal Range and Color Sensitivity are all on a par with the D7000, but DR at base ISO is almost 2/3rds of a stop worse, at equal print size, and at the pixel level almost one stop worse. (The precise figures are 0.65EV and 0.93EV worse).
This is not a big deal because the D7000 has such stellar DR, and the advantages of the lighter weight, lower cost and higher resolution, compared with the D7000, will still make the D3200 an attractive buy for many. The D3200 still has significantly better DR than the Canon 5D3, although worse SNR at 18%, as one would expect. Larger sensors usually have a noise advantage in the midtones.