I can only agree. Do had a really clean, intuitive design. I didn't used it on a daily basis, but - just like latraveler - I was checking out the competition for my company's product a couple of years ago. Out of all the todo list apps I signed up for (and hell, there sure is a lot to choose from), Do was actually the easiest one to use, basically everything was where I expected it to be. It had the perfect balance between the Basecamp feature-rich but complex UI and the glamorous but over-simplified Wunderlist.
Also they must have payed a fortune for their domain, Salesforce probably intends to reuse it soon.