Got my first game in this weekend and though I'd post some thoughts. I'm a long-time WFB/40k player, so I'll probably reference those games often.
We played with only the Core set and no upgrades, but we used the advanced/regular rules. We ran a pitched battle with three terrain pieces.
The first thing I'll comment on is how easy the game is to construct. All the minis are less than 5-6 pieces each and while I'm accomplished enough to assemble the 100+ piece GW minis, I find I just don't have the time to sit and hold pieces together while glue bonds for 15mins at a time. The snap fit nature of the RW minis make for a very quick/easy build.
The game itself plays very smoothly, despite being a FFG product that has more books than it needs and rules that aren't always where you'd think they'd be. Combat is way faster than in WFB and while there's still the "big block units" feel, there's none of the heavy calculations. I felt that damage and figure removal occurred at a reasonable pace (aside from the Heroes) and even though we weren't playing any large Deathstars, the bigger units had staying power.
Terrain definitely is something you should know in advance, because I ended up waking my Oathsworn into a pond edge thinking I'd be fine and then finding out I totally stalled them. I also turned my Spearmen into the spiky barricade which hurt.
The stars of the show in this game were the Heroes. Kari was just a damage machine full of options. She ended up wrecking the Reanimate Archers by herself and later helped cripple the Reanimates unit, moreso, than the Spearmen who were engaged with them did. Meanwhile Ardus wiped out 3/4 of the Oathsworn in one turn. Both felt very powerful and in future games will certainly be big targets.
The siege units didn't feel as flashy as the look on the box art. The Carrion Lancer pinned down the Spearmen in place and inflicted light damage and the Rune Golem went toe-to-toe with the Reanimates and didn't fair well. I definitely like how the runes influenced the battles, but the Golem really needed one more hit point to feel like a better tank. The golems in Descent are always heavy tanks and almost always an auto-include, so I think I was expecting more. Maybe upgrades would help this.
Infantry really felt strong, as Spearmen had good defense and defense options to help them last and Reanimates could come back from the dead. I can see where Deathstar formations are highly viable.
Oathsworn felt solid and I like the Impact hit.
On the flip-side, movement is still fantastic as it is in X-Wing. So much of WFB comes down to how you move, but all the measurements and increments get clunky. Here there's limited movement distances, so no need to split hairs on distance. I feel like there's the fun of any open board game with the ease of a good movement system. And I don't need a tape-measure.
Overall, it's a highly enjoyable game that fits right in between a simple skirmish like Heroclix and a heavy "all afternoon" game like WFB. My next step will be to build with upgrades and consider some additional purchases. Or maybe wait it out to see how Latari fairs.