It is very useful. I captured the signals on the image to compare two logic families for their EMI performance. I believe you get similar results with a more expensive equipment. I use it for 2.4GHz to check BLE antennas as well. You can use far field antennas, near field probes, current probes etc.
It is a little bit slow. But fast enough for that price. And if the measured signal is less than 800MHz, I recommend to limit the upper band with 800MHz. That is the normal mode. Ultra mode is activated when the range includes 801MHz and up. This ultra mode shows some fake signals on some frequencies. I don't know the solution yet. But when you narrow down the range, they disappear. So you can differentiate them from real signals.