The game has both some fairly strong upsides and some fairly strong downsides. For a small description, Cosy Café is a very chill read with some interesting political/mystery undertones, which suffers from how the story is being told and repetitive character motifs.
The music is nice albeit a bit repetitive. The plot overall is interesting, though it can feel convoluted at times; there's a political aspect of several families which control the area and the business around it, and then there's also the aspect of the MC's café and the sustainability of his business. These intersect fairly seemlessly down the line due to the plot, but the reasons around it can feel a bit disjointed or not quite logical at some points.
That being said, the game definitely lives up to its namesake and feels quite cosy to read. There aren't any particularly large dramas or things that you feel will derail the story or become a huge happening, and as such, it's a very straightforward slice of life/romance visual novel for the vast majority of the time, and it works.
The characters are, unfortunately, somewhat forgettable. Some of them are unique and can feel distinct, but some of them quickly fall into the wayside as the plot progresses and it's clear that the update gives a higher focus on another person. This is an issue with the storytelling aspect of this game, that I'll touch in the next paragraph. Back to the characters at hand, they can feel blurred together because they're all submissive. The MC is dominant, but the dominance is asserted in a... childish way at times? And very out of the blue, too. Some times, the relationship between the characters feels natural, but at others, it feels forced and nonsensical. It doesn't help every character is blatantly submissive at basically all points, or is willed into submission by the MC (or appears that will go that way). There's few that escape this, and they're the ones that show no interest in the MC at all; every single other one appears to be going down this route. While their role as a submissive can differ slightly, they tend to blend together at points.
The storytelling has one issue which is that the game follows the god awful forsaken by heaven method that is "Day X" development. I remember a certain game popularizing this, but I cannot stress enough how annoying this method of development is. Because you're making it go day by day, there's an extreme amount of happenings in each day, and because the days are separated by updates, this means that you can go entire days without interacting, seeing, or doing anything with a character you were joined at the hip the very previous day, because this update is not focused on that girl. Lucy, particularly, suffers tremendously from this.
Not only that, but the day system makes the game feel even more divorced from reality than normal for a porn game. It's "day 24' in game, and we go through each of these days one by one. The main character moves in on day 1, obviously, and meets most characters on Day 2. It's Day 24 and he's both fucked and started dating 3 while also being romantically involved with 3 others (depending on how loosely you want to describe it). In other words, the dude's been ACTIVE for these 24 days, huh? Some of the submissive have undying loyalty and devotion to him for... pretty much nor reason. They've known him for 3 weeks, and they haven't particularly gone through anything meaningful together for the vast majority of them (Lucy has a more interesting storyline, but she's quickly forgotten in recent updates in lieu of other girls). They just got spanked a couple times and wooops guess I'm a slavegirl master.
While I can't say that I disliked reading the game, I can't say I liked it either, mainly because of how updates work and because of the day system. Other than that, the game is good. Honestly, you'll probably give this a 4 or 5 as long as you suspend your disbelief. This score is biasedly lowered because I don't like this particular form of story progression.