The Real Time Threat Analyzer has been replaced with the Attack Log. It should still be under the analysis tab, but I haven't installed 8.3 so haven't seen it.
There are some details in the NSP 8.3 IPS Admin guide
Also you might want to have a look at the Known Issues list, there seem to be quite a few issues with this release.
Thanks Peter. Especially for the bug tips.
I like that they have gotten away from the java RTTA.....this is a good thing.