(Contains Spoilers)
Story:

SWWEEET is a romantic-drama with a affinity for some surreal and symbolic design and erotic development, it's a story about a boy and girl with a problematic past that keeps them from being together, it's has themes like coming of age, a love triangle, the nonacceptance of one self, what is to yourself and adolescent guilt.
It's a simple enough story and the writer manages to screw up, to summarize the writer tried to put some good elements that in practice culminated in real bad execution, to explain that, beginning with one of the biggest problems of the narrative it lacks clarity sometimes you don't know what is happening, the dream state sequences were pretty random and did not made sense and it has a more or less ambiguous ending.
The main character is a unreliable narrator and he pulls off dream states for at least 3 times in the manga, even trough his state was contextualize in the middle of the manga, the idea of this "context" sound too far fetched to be believable and even destroys the entire development of the manga as everything can be related to his current "problem" causing his memories to change.
One the most important arcs of the manga, we have a character reveal which feels like a pull off from the part of the writer, looking at the story as a romantic-drama, it fails to capture a sincere relationship between the main couple, they never share a moment or any interest.
The use of the bullying theme is ridiculous as to how it was approached, a girl that never report the bullying that she is suffering and the motivation as to why is because she "need to be cheerful as she doesn't want to change herself for her old love", it feels forced, looking at another manga that did it right you have A Silent voice where our main heroine is literally deaf and she tries to ignore the bullying as she want to be part of her class and because a promise she made to her sister, it's far more convincing if you read it.
The symbolic image-dry is not really meaningful to the plot being more a deviation from the story than something to add, there's not a lot of interpretation, you have a girl that uses a strap on her bag in one chapter and in another the mascot on her strap becomes the monster for the boys nightmare for what reason? because he likes her to the point of remembering something useless she wears? it would be better if it was something that meant for the both of them, for example if the main character had given this item to her in the past as a gift.
The tone goes from cartony to creepy and it doesn't know where to stay, for the most part they treat thing like brain damage as a joke, as tone is not a very important aspect when it comes to tell a story, you can tell a story about going to the mall and it can be either spooky or funny it doesn't matter but there's a problems with the story it does tone shifts in unappropriated times, e.g. the main-character is looking for answers goes to the pond and finds his classmate amount being raped, tries to "save her" and in the end after the dramatic fight it ends in a joke, it's totally out of place.
The pacing is slow at the first 3 chapters and afterwords we have big chunk of information being skiped, most of the characters pulling various plot cards to accelerate the story.
For the most part there was not treat to anything, not to the main character or to the romance, mostly anti-climatic.

Characters:

The characters are one dimensional for the most parts, the main protagonist Susumo can be characterized as a useless person, the main heroine Sakura is just crazy and the protagonist's brother Tsutomo is the "reliable" male, we have smalls changes but nothing substantial to these characters.
The first big part of the manga which is more of a self-reveal story, the main character passes thought a change but it doesn't bring a array of personality to our hero, he just change one trait, from being useless to being "reliable", that doesn't really happens to the heroine thought as she doesn't have a arc and if we look at their romantic development we can see that they don't share any interest or any dramatic conflict, he likes her since he was a kid because she was "nice" and she begin to like him when her memories get back to see that he is "reliable".
The side characters felt stupid you have one character that is a living piece of plot fuel and his girlfriend who has one of the few tragic or dramatic reveal but they don't even give her space or a arc, even her disease is not disclosed, a bully that has no motivation for bullying people but in the end is a emotional girl.
Some plot points at the end were dropped, the brother is never found and there's zero explanation to it, the main heroine stop acting like a bipolar bitch and that also goes to the bullying leader that goes from being a bully to being a pure emotional girl.

Art:

It's on par with most manga, the composition felt lacking and the panels were boring, the design of the surreal images was average as there was no meaning to them but everything was still well draw, having the same style as your usual romantic high school manga.

Enjoyment:

Could have been much better, lost of potential i would say that it wasn't very bad but i wouldn't recommend it to anyone, especially when you can find a much better one with similar themes but better execution.