If you're interested in getting a quick run through the philosophy of the Hellenistic period, this would be an adequate primer. Probably best used to point the way to primary sources or more thorough scholarship. Designed as an introduction, it should not be faulted for often skimming difficult issues.
If you have some philosophical background you will likely be able to identify the times when Sharples makes an assertion without much argumentation (again, since this is an introduction, I'm willing to overlook some of this). If this is your first exposure to the Hellenistic period, you may want to take some of his claims with a grain of salt.
It's unlikely that there is another, more concise introduction to this period around, so this fills a need. If you're looking for deeper, more thorough scholarship on the period, then look elsewhere.