Well, good things first: I love the imagery! The ISS is beautiful, and mixed with Varric's narration of events, it makes for a pretty enthralling experience, to hear your Warden's tale repeated back to you like a beloved or well-known legend. However, I'm a little disappointed that after three times, I have not managed to get through the ISS without encountering a sound or story related bug :C
The first time I started up the ISS (using my default world state) I was able to get all the way to the anvil of the void arc (this was also the furthest I was able to get in the ISS out of my three attempts) before I started to experience issues. First, Varric's narration ended, and I was left with a few images of the broken anvil set to the background music before my screen went black. The music continued to play, so I kept the ISS playing for a few minutes before I realized Varric had not stopped narrating to up my suspense. 
The second time I started the ISS (same world state) I only managed to get to the Redcliffe story arc before things started breaking. First of all, a scenario where I'd chosen 'Connor lives' was switched to 'Connor possessed' (judging by the imaginary, anyway...), and secondly, Varric's narration stopped. The music once again continued to play, however.
The third time I started, I got a little bit further than my second attempt, making it to the Urn of Sacred Ashes arc. However, Varric's narration once again came to an abrupt end, and another story decision I made... SEEMED to have been changed? My tapestry has an 'Untainted Urn' saved, but I was definitely shown an 'Tainted' urn in the ISS... however, it showed an Untainted urn shortly after... so maybe when the ISS has this breakdown, it just starts showing all possible options? D:
I don't think I'm going to be filling out any more bug reports today, just because my three failed attempts all seem to be the same issue? and I don't want to spam you guys... :x
I'm going to keep trying to see if I can get through the ISS ONCE without issues. Oh well, least I can say the background music is lovely. :3