Descriptive and brandable names both have their advantages. There is demand for good ones in either direction, and descriptive names have to be brandable to some extent. Regardless of CPC rates and searches, if a domain is too long or overly narrow in scope (i.e. hp500printerdriver.com), nobody will want it, except maybe SEO spammers, who don't typically spend much on domain names.
The "exact searches per month" can be used to gauge popularity of a search term to determine possible demand for a domain name, but it does not necessarily indicate traffic for the domain. 50-150 exact searches realistically equates to less than a visitor a day for the type-in traffic to the exact match .com.