I thought HD might have somewhat improved graphics or a new engine, but this is just an emulator with a higher detail ship. The textures were already pretty grungy and the HD mode doesn't really improve things. Not worth a play.
While I like shmups well enough, this port is FANTASTIC. Lots of quality options, as expected from M2. The game includes the fun branching paths and cooperative play Taito made famous with this series. Lotsa lotsa fun. Right up there with Crusin' Blast on surprisingly funtastic Switch arcade ports.
Really fun one, probably the best Darius on Switch right now. Great replayability, with multiple paths and endings. Graphics are crisp and look nice, the grab system is really fun to use and discover what every enemy can do when fighting with you. There is some slowdown very occasionally, and there's no option to turn off infinite continues.