Art like this is why I watch you. The shading of the lion itself is fantastic, and you really complete it with a perfect texture choice. The green outline is perfect, and really makes the lion 'pop', and it also draws your eye to the painting.
The orange in the background almost looks like you got lazy with it, though, but as a whole, the background adds great contrast.
The lion's neck fur shouldn't be quite that ruffled, and the fluff coming of the back of the cheek seems a little long, since this is actually a lioness. Other than those little things, the lion's anatomy is almost perfect!
Great job on this!