I wouldn't necessarily take client praise as a testament to being good or bad. When I started out I was pushing WP sites; I usually gauged things by complaints (very similar vibe to when I was working on cars).

I have had very few calls / emails about complaints with the WP admin area, though I do/did generally drop them into a less privileged account with less flashy buttons to break things with, as well as set their dashboard up with some notes about how to accomplish tasks specific to their usage (how to post / edit / delete, how to clear the cache manually if they had to, etc).

I might be in the minority there, and I feel like that contributed a bit to the no-complaints thing... but even a vanilla WP admin area is very usable.

I would be interested in finding what those other options are, in all my career I never had any client tell me a CMS it's simple to use.

I feel like people don't take advantage of how easy it is to create a simple user interface for a Drupal site. Create a new page for the user on login that lists the most frequently used functions with another link for advanced functions. That said I die a little every time I see the markup D7 produces.

I have over 50 clients (small business owners) who run WordPress. Many came to us complaining about their old CMS, sometimes even WordPress.

After building their site for ongoing management ...correctly, and tutoring them many were/are thrilled with WP and the content editing process.

The key is implementation and tutoring. Asking a client to manage raw markup, or handing the keys over with no tutoring are recipes for dissatisfaction.