eighten

Well... let's see. Al's examples of triangles, lines to lead the eye, balance, etc., are good ways to begin evaluating the tree as art. If the design did not hold together, it would be hard for the viewer not to focus on ways in which the tree could be improved rather than any sort of artistic power.
So, if Al feels that this tree expresses something to the viewer; if he feels that this tree has some sort of profound beauty, than it is art. Is it good art? I would say no, because I don't find it to be particularly striking or powerful, and I don't find it evoke any particular emotion(s).
Why? As I think carl is pointing out, the placement of the jin on the underside of a bend is a little distracting and prevents the jin from having the emotional weight that it should. The foliage looks good, but is unremarkable. The nebari and potting do not suggest to me that the tree has a location in nature - it looks homeless to me somehow.
I would say that what has happened in the progression of pics is a tree that was not art and not a good bonsai has become (or has been planned to become) a mediocre bonsai and a mediocre work of art.
Now, looking at Al's gallery, the pictures are a little small but it looks like there is some pretty decent art and some real nice bonsai there, IMHO. In general, I would say that there are two basic ways in which a single bonsai can be good art (and when I say "tree" I mean the tree, the planting, the pot, everything together:

1. The tree has nothing that one could call a design flaw, and exemplifies good bonsai technique (which takes care of many issues of design such as uneven proportions, unnatural-looking leaves & scars, etc.). The tree also "feels like art" to a high degree. It is emotionally moving, it feels unique, magical, striking, vibrantly alive, etc.
2. Or, the tree is as described above, except that some rules of design or some rules/techiniques of bonsai have been altered from tradition in such a way as to subtract nothing and possibly add to the aesthetic and emotional beauty of the tree.

As I gain a greater understanding of the traditions and processes of bonsai, I will probably see new ways in which bonsai is artistically valuable. I am confident that the above two "ways" are basic enough to be only expanded and clarified, though.
I (or you) must ask, is there anything that I can see which could be removed, added, or changed about this tree that would make it somehow "better" to me? If not, does it seem unremarkable to me? If not, it is probably good art... to me. If I am a naturally talented artist or if I have studied art and have gained a deep enough understanding of it, it is probably good art to a lot of people, and that is the good art that art critics and museum patrons like.
Does that answer the questions?

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~john, Midwestern U.S. zone 4a