(Won't be reviewing White Nights here as I've already read it and reviewed it in the past.)

I love me some Dostoevsky man, he always hits the spot. This short story collection contains: White Nights, A gentle creature, and The dream of a ridiculous man.
My really short review of the three would be this.
If you're feeling hopelessly romantic; read White Nights.
If you're feeling Nihilistically depressed; read A gentle creature.
If you're feeling spiritual and hopeful; read The dream of a ridiculous man.

A Gentle Creature.
This was my least favourite of the bunch, it's still a good story, but Dostoevsky sets himself such a high bar with his other works that when one of his stories is only a 7/10 you can't help but feel disappointed. Purely personal opinion of course but i found the themes and writing in this one a little mundane in comparison to the other two short stories.
You have this main character who is essentially an egotist, everything revolves around him, his opinion is of utmost importance, and everyone around him must adapt to his ideas. He marries a very young girl (Because he believes he's "Saving her") and then gets annoyed when she occasionally acts like a young girl. He's also blinded by his own self-importance; when the girl kills herself he refuses to truly pin the blame on his own actions. He stupidly thought everything was fine in their relationship when the whole time he was caging this young girl up and emotionally manipulating her. A trend I see between this story and The dream of a ridiculous man, is that both involve a man corrupting and ruining something innocent, but A Gentle creature is a much more sinister example: A man corrupts a girl out of sheer egotism and then refuses to take the full blame.
Moving onto the next story.

The Dream of a Ridiculous Man
This one honestly made me a little emotional. The story is about this unnamed protagonist who is suicidal, he's decided to shoot himself with a revolver tonight. However, as he's pondering over whether or not he can actually do it, he dozes off in his armchair. The dream that subsequently follows is the main plot of the story. He dreams that he shoots himself in the heart, that he dies and has a funeral. Then as he's lying in his grave some strange creature lifts him up and carries him off into space. Eventually he lands on a strange planet far away that is identical to earth in all ways... except one, that the people are different. Without going into too much detail, the protagonist realises that he is literally in the Garden of Eden and is witnessing humankind before the fall, or before the first sin. It's a utopia. Then you get the saddest part of the story, The protagonist accidently corrupts them all and drives them to sin. He discovers that he's playing the role of the snake in the garden. He witnesses all the turmoil and vice befall them that has befallen modern humankind, and he's devasted. When he awakes from his dream it's simultaneously heartbreaking but also hopeful. He realises that the requirements to produce an environment like the Garden of Eden are incredibly hard, but also possible. If everyone tomorrow were to follow the golden rule, to be as meek and innocent as little babes, then humanity could really become paradisal in its structure. 
I get why some view this story as stupid, even Dostoevsky calls the character "A ridiculous man." But I love it too, because this story is Dostoevsky at his most hopeful and idealistic, the "Holy fool" is a common character archetype in his novels, and the protagonist of this story might be the most extreme version of it. To truly think that we can attain a world without sin or vice, without deceit or corruption; it seems ridiculous, but as the protagonist points out, it isn't impossible.
Of course, if you're an Atheist or not of the Abrahamic religions, then this story becomes nothing to you. But to me it was really beautiful.