Neal: It's absolutely jam-packed with features and if you're someone who already has Shovel Knight, it's a heck of a free addition. As a solitary game, it's a much harder sell. Like you said, it's more of a curio or bonus than something that could stand solely on its own.
Each of the game's four levels is divided into nine stages, and by the time I reached stage nine, I was more than ready to move on to something else. Shorter levels with more variety would've alleviated this problem. There's a good game here, but it's best experienced in short bursts. If you keep hoping that Retro Studios would make a third Donkey Kong Country Returns game, you are probably the target audience for Jet Kave Adventure.
If you are a fan of Lovecraft and the Cthulhu Mythos, The Call of Cthulhu: The Official Video Game (apparently its full title) will hold some appeal to you. While familiarity with the source material is not required, it probably helps, but I can safely recommend this game to any fan of the cosmic horror genre. There are some rough edges, sure, but it's well worth the journey overall, especially around this time of year.
Even if you've played these games before, I'd say this collection is absolutely worth picking up. It's wonderful to have them all on Switch since they were spread between three platforms originally (3DS, Wii U, Steam), and the Mighty Switch Force games are just plain fun and full of personality. I would like to have seen a collection of concept art a la the SNK and Street Fighter collections because Digital Eclipse has spoiled me forever with that kind of bonus content, but that doesn't take away from the experience, and I will never, ever get sick of kicking that ugly baby.