Finally got around to playing this yesterday.
The strong point is definitely the presentation. Extremely moody and atmospheric, with lots of appropriately Gothic pipe organs. There's heavy use of solid black in foreground, giving everything a dark and somber tone. But despite the overall gloomy theme, there is also some spectacular use of color. The forest is as lush and vibrant as it is gloomy and oppressive. There's some gorgeous gradation of color in several background skies. The sprites are gorgeously detailed and animate great. Firebrand himself looks stunning and his alternate transformations look fantastic. They really made sure every form looks unique while still looking ultimately gargoylish. Even their walk animations have different personalities.
Exploring the world is a lot of fun. You select what stage to go to by flying around an overworld map and swooping down to suspicious-looking locations. The stages themselves, while often featuring alternate paths, are generally pretty short so it doesn't feel punishing to go through them a second time once you've acquired an ability that allows access to previously unreachable areas. There are tons of helpful items lying about, such as empty flasks (which you fill at a potion shop), blank scrolls (which you buy spells for), and a surprising number of permanent HP upgrades. You'll need all the HP you can get, though, as it doesn't take long for bosses to do multiple HP of damage with every hit.
The game is also not easy. Aiming your fireball is incredibly finicky. There are a lot of enemies such as bats and flying eyeballs that are really difficult to hit, and the difficulty is compounded if you're using your default weapon which can only fire one projectile at a time. While you do acquire alternate weapons with increased rate of fire as well as bigger projectile hitboxes, and your transformations each have their own unique attacks with some scenario-specific uses (the Aerial Gargoyle can cut the vines in the forest level, for instance), this brings up a small issue I have with the game: Switching out weapons and choosing alternate forms is cumbersome and awkward, requiring you to pause the game, select the appropriate icon, press Y, then unpause the game. Generally it's not a big deal, but there are parts of the game where you'll find yourself rapidly switching from one form to another and it tends to hurt the flow of the game. Even with a variety of attacks at your disposal, though, there are narrow corridors with multiple flying enemies that are just a huge pain.
While there are some parts of the game that can be pretty difficult (some bosses will take multiple tries), Demon's Crest mercifully allows you to continue indefinitely, usually not far from where you were when you died. This is a great feature that allows you to learn from your mistakes without having to deal with re-doing large stretches of game or fumbling around with reloading game data. Also, the game never tells you where you are "supposed to" go next. It's pretty much up to you to explore, discover new abilities and figure out where to use those abilities. While this can lead to some wasted time (some levels won't even appear on the overworld until certain criteria have been met), it does make it all the more satisfying to be the driving force behind your own progress.
The game's story features some pretty nice cut scenes, and the title screen reveal is fantastic. You should definitely wait through all that the first time you play. Another interesting feature is that you can actually challenge the last boss pretty early on in the game (I won't tell you what happens if you beat him). And be sure to swoop down on even innocuous-looking areas on the overworld. There are a couple of hidden bonus games, including the level 3 head-butting minigame that earns you a life upgrade the first time you beat it.
I've still got a ways to go (I've only gotten my Ground and Aerial transformations so far), but I'm quite enjoying all the things Demon's Crest does well, despite some of its more annoying features.
