The artist claims this is his first piece using his tablet. On first glance, I didn't believe it. Good shading, excellent conformity to canon proportions and design, and great color choices all make a good Lucario piece. I'm pretty sure I've seen this pose before, but never at this angle. A few fill and shading problems are noticeable, but not on the first glance.
As I stated, I am pretty sure I've seen this pose, of Lucario mid-punch, before, but if it isn't broken, don't fix it. It's a dynamic, exciting pose that makes us wonder what's on the receiving end of that punch! Still, I haven't seen it quite at this angle, which puts the most emphasis on the determined look on Lucario's face and its animal-like balance. That expression is determined and passionate, but the mouth is not visible, giving us little clue as to whether this Lucario is disciplined or centered. This wisely robs us of an understanding of whether this is the dour, serious Lucario of the eighth movie or a more general Lucario with a more cheerful personality. The piece showcases the species, not one particular character, though that character is not specifically excluded.
That said, there are some minor issues with this piece. The contour of the left foot (viewer's right) seems a bit off, and while not technically flawed, the yellow tufts of hair seem static and more like spikes. The contour of the tail is not clear and the shading meant to convey it is slightly bumpy. The black shading on the eyes is just a little too prominent. There are also minor problems with the shading on Lucario's rear.
More noticible are the fill problems, small white artifacts near all the black lines. They are most noticeable on Lucario's left paw (viewer's left), his forehead, and the tips of his ears. While they don't detract substantially from the piece's impact, they are noticeable enough to essentially rule this piece out as wallpaper: the more you look, the more you see them.
This is an excellent, pleasant piece that wows on first impression, and even second viewing. It isn't covering any new territory of Lucario fanart, but it does take a fairly new approach to a common pose. Shading problems and white splotches make the piece less pleasant to look at continually, but who stares at art for long periods of time anyway? It's still better than anything I could do.