I finally finished Pictures of Hollis Woods, by Patricia Reilly Giff.  Here's the review:

What I liked:

• I didn't read the dust jacket before I started it, so everything was a surprise.
• Hollis and Josie (her elderly foster care provider) develop a really interesting relationship.  Hollis has never cared for anybody much, until she finds someone who really needs some care.  Hollis protects her, feeds her, handles her money, and learns to love her.
• The "pictures" of Hollis Woods are the pictures she draws as a talented artist, and the author describes each with an accompanying memory.
• The picture, chapter, picture, chapter lay out helped transition between past and present without my thinking "Wait, is this now, or a different time?"
• Hollis has great emotions through the book.  It's hard to imagine a twelve-year-old feeling so much guilt and anxiety about her behavior.  But Giff writes it very convincingly.
• There's a great happy ending that is a perfect picture of unconditional love.
  

What I didn't like:

• Waiting in suspense for one-hundred twenty pages to find out what Hollis did while living with the Regans.
• That Steven doesn't tell his parents where Hollis and Josie are.
• Hollis calls Mr. Regan "the Old Man."  This drove me nuts. Nuts.