Just got this the other week and I'm having fun with it. I like how Steinberg allows you to load separate VIs per track or as a VST. Neat. Multi channel VIs like HALion Symphonic Orchestra or Kontakt 2 work soooo much better on Cubase than in Logic. Also, the rendering is much better than trying to do it on MOTU DP5. There are still a few bugs that need to be worked out but nothing too substantial.
I was intially worried about using Vienna SE on Cubase but it works fine. My only gripe is that of Cubase's notation editor. Unlike Logic or DP, it seems to interpret MIDI messages much more specifically than the others. If I'm playing a syncopated 8th note line it sometimes uses 16th notes tied together or some such nonsense. DP has the best transcription of the lot in my experience but is a nightmare on other levels to navigate around on. SO I'll stick with Cubase Studio 4. Also, it's nice that the program runs pretty light and the MOtif waveforms that come with the HALion player are really authentic. I sometimes miss my Motif board (I have a Kurzweil PC1SE) so it's great to get those sounds back.