I found this really frustrating on hardcore. I've completed the game as Lucas, Katrina and Reinhart on normal (with the expansion) and not really had any problems - died about 10 times in total. Hardcare just makes most of the bosses/some named characters incredibly tedious though. Turns into a 15 minute kitefest and Rajani is extremely irritating. The first part is relatively simple once you get the technique right. So you have to go through all of that only to get immediately killed by the second part. My AI partner pretty much lies on the floor throughout the fight.
It's a shame Obsidian went down the walking tank route on hardcore. General mobs are still interesting and dangerous, the bosses are just silly though. It feels like you have to find the one single exploitable weakness or lose, then keep doing that for what feels like forever... and of course if you get stuck dodging into the edge of some scenery get ready to reload...
