I've used Experian profiled data for mail Marketing Campaigns over the last decade. I don't personally rate it, the response rates are generally poor (<0.5% response rate)
No idea on the email data, I would imagine the quality or accuracy won't be great if the address data is anything to go by.
People seem to get drawn in because it's cheap, I have also used data from other similar providers that are just as bad.
My advice would be try to acquire data from multiple, more targeted sources rather than a block of data from one source that a lot of other people will also be trying to market to at the same time.