Apparently, yes. The AIS3 has a better processor than the AIS2. Because the AIS2 had a poor processor, Nasa filtered out some AIS messages so that the processor could cope. With the AIS3's better processor, they don't have to include those filters, so the performance is said to be better.
However, remember that it's still a switching receiver - it only listens to one channel at a time. Personally, I'd rather get a genuine dual channel parallel receiver; the Advansea AIS100 is about the same price as the Nasa.