I just finished my first story (10 chapters, almost 100,000 words), which contained quite a bit of direct thought. The story from which mine derived used it, and I liked it. Like everything else in my story it was an experiment and it was far from perfect, but reader reaction was uniformly positive. I received dozens of emails and public comments in the vein of "I liked knowing what the characters were thinking." Although I received negative feedback (or, ahem, constructive criticism) on other points, I don't think anyone complained about the use of direct thought. One fellow was put off at first by the use of italics but then sent me a retraction, indicating that he'd tried to skim the story the first time and was able to follow it better the second time. Based on reader reaction, I would not hesitate to use direct thought again, though I would always try to be careful with it.