Yikes, it looks like it's been 8 years since I played the first Mighty Switch Force! game on 3DS. I just finished the second game last night, which has the awkwardly punctuated title Mighty Switch Force! 2. The game has only 16 stages, but overall it's a similar length as the first game in terms of the time required to complete. Like the first game, each stage has a "par" time that you can shoot for, which increases replayability, and there's also an optional collectable in the form of an "ugly baby" in each stage as well.
For about the first hour and a half of the game I felt exactly the same way as the NintendoLife reviewer, namely, that the game was way too similar to the original. Unsurprisingly, the beginning of the game is basically a retread of the original game's mechanics, presumably in order to get new players up to speed, but I got a lot more interested in it once new mechanics started to become more prominent. The firehose mechanic doesn't really change things up that much, but it does introduce some satisfying Pipe Dream-like puzzles. One of the biggest new additions is a block that locks when you're standing on it, and although it took a while for the way it works to really click, ultimately this leads to some very novel and satisfying puzzles as well.
I'm not a fan of speed running through games so I didn't bother with the par times, and I didn't bother collecting all the babies, either, but even though I started off not particularly caring much about the game, in the end I was won over and quite enjoyed it. The game has WayForward's expected sky high level of polish, and although most of the visual and audio designs were already seen in the first game, all of those elements were still enjoyable here. Overall I agree with those who say because of the short length this feels more like an expansion rather than a full sequel, but for fans of the original this is still an easy recommendation.