To take that all in at once, I'd say yes and no to Daniel's points. Just to go through that whole feature set from the perspective of my sister, a common user looking to replace her 822...
SensorCore: Why give up a FitBit for SensorCore? What is the selling point on that feature over the fitness trackers so many average users already have? My sister likes her FitBit One, and I don't see anything thoroughly explain SensorCore in a way that shows it as not only an alternative to a typical fitness tracker, but an improvement on it. On the general level, why SensorCore over S Health, and what about Apple, the king of marketing a gimmick as more than it is? It doesn't seem like Microsoft is meaningfully focused on this feature, given the lack of media coverage.
Dolby Digital: What does this do for the music? All my sister cares about is that the music plays when she wants it. When talking high-end audio branding, Beats is the brand that sells, and Apple has that. On top of that, who in the mainstream will own headphones to pick up the subtleties this might offer, and who in the crowd will honestly care? I mean, I like having the equalizer in my 920, but I could easily live without it.
Sunlight Readability: Good to have, but as soon as you compare it to "non-Lumia" offerings, I both wonder how this feature stacks up against the apps/features missing in the 830, as well as why this feature matters to the 820 upgrade crowd (let alone the 920), since this already exists on the older devices.
OIS: The masses won't know this much. They won't care what it means, and it's why Apple and Samsung are able to easily get away with inferior cameras--the masses (who you're trying to market this for) don't have high standards.
Honestly, my disappointment isn't even in upgrading from the 920. It's that this is named and marketed as an 810/820/822 successor, and it's hard to even argue that point. It's like an 820 with a batter camera and a couple of minor features, and that's not going to be enough to convince users to sign up for 2 years of what will essentially be the same phone from 2012 that they want to replace. On a personal level, my disappointment is in the lack of effort in pushing boundaries with Windows Phone, and the overall lack of quality devices. I wasn't going to go from the 920 to the 830, but I was at least hoping to see Microsoft show us some real commitment to being a hardware manufacturer. Instead, I'm left staring at two phones which are somewhat redundant (730/830) and marketed as more than what they are. That just gives me a bad taste in my mouth looking forward to my upgrade because not only is there a near-future device to wait on, but I'm also unsure that there will be something to move towards in the future because Microsoft looks so uncommitted to giving us high-end hardware.