In some ways, this is a very typical picture of Pikachu done in a super-cute, softened style. What it lacks in originality it makes up for in excellent technique and superb posing.
Pikachu's pose is clear and reasonable. Though the proportions of Pikachu don't quite match the most recent few generation's official models, it is still within the range of what canon has established, with shorter legs and a fatter body like the Generation 1 pikachu, but a long body like the anime and more recent games.
A certain degree of neoteny has been added to the design to enhance the sense of cuteness. Large eyes, small cheeks, small, rounded paws, and a shortened, widened tail all make Pikachu seem younger and cuter. The slight mess of hair on its forehead also add to this effect. If I may there is one minor technical problem here: Pikachu's right paw (viewer's left). It seems to round off in a way that defies the bone structure implied by the other arm. The upper/outer edge should be just a little straighter.
While we're on the topic of technical things, I really liked the choice to soften and make more orange Pikachu's cheeks. The color used in canon is a bit harsh, and this adds to the cute, innocent, "AWW" effect.
What really makes this piece stand out is the very subtle and superb shading. I did not realize it was shaded at first, but slight shadows have been applied on the "undersides" of Pikachu's body, including a very well-done nose shadow. The highlights are also especially well-done. The weakest point in the shading is the ears, which appear to have been lightened more than the forehead and tail-tip have. Still, it's good shading, just not as good. Certainly better than anything I could do.
The pose suggests a pikachu who trusts you so much it'll show you its tummy, like you're its loving trainer. You can almost put yourself in Ash's shoes. The neoteny wants you to take care of it. In that respect, it's a masterpiece.
The heart adds to this effect, but it's also a bit of a cliche. The pose of a cute pikachu rolling around, being all cute, is also fairly trite, but a certain degree of cliche is inevitable for a character who's practically 20 years old. You don't need to be original when you're this cute.