I agree with you that this sentence seems off-kilter, though I would not class it as outright ungrammatical. The reason I find it jarring as presented is that midway through the sentence, which is otherwise simply a list of the woman's attributes, Hemingway jams in the man's parenthetical opinion, "but he liked her face".
Your proposed amendments resolve this incongruity by punctuating the original sentence so as to turn it into three self-contained elements which can be read and understood individually.
However, perhaps we should cut Hemingway some slack here. The entirety of the paragraph in The snows of Kilimanjaro from which you have excerpted the sentence in question reads as follows:
Now she came in sight, walking across the open toward the camp. She was wearing jodphurs and carrying her rifle. The two boys had a Tommie slung and they were coming along behind her. She was still a good-looking woman, he thought, and she had a pleasant body. She had a great talent and appreciation for the bed, she was not pretty, but he liked her face, she read enormously, liked to ride and shoot and, certainly, she drank too much. Her husband had died when she was still a comparatively young woman and for a while she had devoted herself to her two just-grown children, who did not need her and were embarrassed at having her about, to her stable of horses, to books, and to bottles. She liked to read in the evening before dinner and she drank Scotch and soda while she read. By dinner she was fairly drunk and after a bottle of wine at dinner she was usually drunk enough to sleep.
From this it is clear that Hemingway is setting out to describe, in a manner that reflects the unstructured casualness of the man's thoughts, both the objective attributes of the woman herself and the man's subjective impressions and evaluation of her qualities. The aggregate description is therefore stylistically rather rough around the edges, but it is consistent with a narrative whose locus seems to fluctuate between the author and the protagonist of the story.