Pantheon is a GREAT host for Drupal and Wordpress!
What do you like best about the product?
Multidev environments, Dev/Test/Prod environments, Site Dashboard, ease of use to get local files, code updates
What do you dislike about the product?
They don't support Drupal Multisites, when sites in development Freeze, a little expensive for smaller sites
What problems is the product solving and how is that benefiting you?
Hosting large complex Drupal website with lots of traffic