I just finished this, and I...didn't really like it? Which was disappointing, because I loved the first game. But for me, a lot of this one just felt bad to play. As a few people in this thread have already mentioned, combat in this game is negligible at best. I'm gonna go one step further and say the combat in this game is bad. At the default settings, enemies hit way too hard for how aggressive they are, and you don't do nearly enough damage to compete. I think it's fantastic and laudable that you're allowed to adjust both levels of damage from menu sliders, but I don't think I would've realized this was an option if I hadn't read it here first. I also appreciated how there's no contact damage from enemies, but at the same time when their sprites are right on top of you you can't actually hit them. After I adjusted damage levels to a point that felt better, combat eventually became trivial after finding some weapon upgrades. I could've kept tweaking the menu sliders as my character got stronger, but at that point it feels like I'm balancing the combat system when Tom Happ should've done that already. And he's already proven in the first game that he knows how to do Metroidvania combat, so it was pretty jarring to get thrown into combat that felt this bad in the sequel.
I'm also torn about whether the near-total lack of handholding (in terms of exploration) is a good thing or not. On the one hand, I understand that you're supposed to be exploring as much of the map as possible, but more than once I found myself completely lost with no clue where to go and had to look up help. This was typically before I unlocked fast travel, so I got frustrated with constantly retreading the same streches of the map. Or I'd be going in a direction that I thought would lead to the next area, but instead led me to an optional item (which usually upgraded some other weapon I hadn't even found yet). Admittedly I don't know design-wise what would've helped these situations, but overall I found the game often just a little too opaque in terms of directions. Looking at the map screen, I also had some trouble discerning where available exits were, but that one could just be me. I don't think increasing the contrast between walls and exits on the map would've hurt, though.
What did I like about the game? The whole environment and atmosphere were fantastic. The pixel art is often stunning, especially in the larger enemies. Exploring the map was fun, as it always is in these sorts of games. Moving around as the drone felt great, which almost everyone on this page so far has mentioned. Moving through the Breach and figuring out how it connects to the other map was another highlight, and often made me feel like a smarty-pants. I also liked piecing together the story connections to the first game. You get a nice collection of abilities by the end of the game, but I also felt like it ended really abruptly right at the point where it felt like the world was about to open up. I wanted to play more with the gas cloud ability, but then the game was over basically as soon as I found it.
At the end of the day I think it's a good game, but it wasn't what I expected and I didn't have that much fun with what it turned out to be. The skeleton of something very strong is there, but its flaws (for me) are also on full display from the beginning. Overall I can't help thinking that it feels a little unfinished.
