I think jjpeabody did a great job of giving you an honest and upfront critique on your painting, especially concerning your values. That doorway in the structure could have been pushed way darker, and the whole image looks like a faded print of a picture as a result.
I do have one issue with the critique though. Sometimes (in fact a lot of times) shadows are more desaturated than the lighter areas in a painting. Shadows are the absence of light, and without it, you (almost) never see the full brilliance a local color can evoke. BUUUUUUUUUUT... shadows aren't automatically grey either. And I think this is what jjpeabody was trying to get at. As a beginner, we generally think shadows=black. This is BAD BAD BAD. Instead, try blues and purples. Experiment. A blue over the yellowish brick of your building will produce something greyish, but it will have a ton more life than if you use black or grey. This is called "using temperature to turn form". because you are using a "cool" color to show the form of a warm object. As you learn more about color you will learn how to use other colors in the shadows even "warm" ones instead of cool ones.
and i'm definitely nowhere near as good as jjpeabody at painting.
i constantly go back and forth on photo referencing thing. Some food for thought though: what happens when you draw from reference? you learn something new. So what can we say about artists that never use references? are they never learning?
I've lately tried painting from photos, then superimposing the image over my painting to see how badly i did "seeing" the image, and then correcting my painting. I think we artists are always shooting to be able to create without references- but also should be smart enough to know when we have to pull out the mirror or find a picture because there was something else we haven't learned or might have just slipped our memory.
I'd have to agree that the legs aren't that bad in terms of length, but they definitely feel off. I'd love for the artist to post the photo he based his artwork off of. It seems to me that the contours might be tracing the photo, but landmarks like the fold of the ass cheek into the hamstring, or the indentations behind the knee might be changing the perception of femur length. One thing I looked at straight away was the number of faces compared to the length of the leg, and the figures head is so small that, by that standard, the legs are fine, but then i look at the arms and torso, and by that standard, the legs are too short. so maybe the arms are too long? the torso to thick? or even the head is too small and once it is fixed- then the legs are too short It should also be pointed out that the black footwear is contributing to the short look of the legs. There is more leg there than we can see when we judge the length at a glance