He mentioned the difficulty progression on normal mode at the start being a little too quick in ramp-up, particularly between Jin'rokh and Horridon, which was adjusted to smooth the difficulty curve. He also brought up the linear nature of the raid, which Blizzard had heard complaints about from players, where the option to try different bosses rather than the one after the other structure was superior. He mentioned that the underground cavern section could have been a great zone for more variation. Lastly, the Ra-Den encounter didn't quite work out how they'd hoped. The sense of mystery was great, but the tuning was difficult without the usual level of testing. Players beat the fight by bypassing several mechanics, and thanks to the limited attempts, the developers didn't feel it was fair to fundamentally change the fight while limited attempts were still ongoing.
Pat went on to ask about the levels of trash, which has been a contentious topic in LFR particularly, thanks to the lack of drops, but the devs still feel it's very important for pacing, and that the trash becomes far easier and an achievement in itself in time.
They then went on to cover Vodka and Exodus' break-up, specifically Killars' facebook post discussing the pressure and the burnout of players thanks to the content pace and structure. Ion felt this wasn't new, even citing the Sunwell grind, when guilds like SK Gaming raided for 20 hours over 2 days to get a world first kill, which, at the time was unprecedented. Ion felt that is was an arms race, based around time, and that it was something tricky indeed to solve. Blizzard had tried some measures, but players always work around them.
Pat then asked who Ion thought was the primary target audience. Raiding, Ion said, was an activity for all players. The devs, though, did feel that they wanted to get more group content going, and that LFR was great, but didn't replace the co-operative social experience that was group raiding. He specifically mentioned the "friends and family" guild, who were previously served by 10-man normals, but maybe lost out on that experience.
They went on to discuss the determination buff, added in patch 5.2, which has worked out really well, and that the devs were seeing a substantial drop in players leaving LFRs after failed attempts. This helps with LFR in general, shortening queues, lessening the incomplete runs, and generally improving the experience as a whole.
It's a great interview, with lots of other great points, so do check it out, and keep an eye out for other developer interviews over the week.