Offer hundreds of free themes (templates) to choose from.Intuitive user interface (UI) and SEO friendly.No hosting required (Freely available, followed by .wordpress.com).Smaller learning curve.
Room for Improvement:
Doesn't provide option to modify PHP and CSS files for free members.Not scalable for big and complex websites.No option to monetize the website (Affiliated links or Advertisements).
No doubt, wordpress.com offers great features from newbies to experts. In order to improve the product, some of the basic and important features should be freely available (Like Uploading Custom plugins and themes).