It feels like checks are barely hanging on. I started using Simple 4 years ago when I switched jobs, partly because it seemed like more and more places were posting signs that they didn't take checks. Since Simple doesn't really have checks, except ones you have them send by using the website, that seemed ok.
In the 4 years since, I've had a few instances where I needed checks. I have a plumber I like, but he isn't really a businessman, and so he wants cash or a check when he's done with work. The only tradesman I've dealt with that wasn't happy with me sending a check from Simple. He does good work though. I have some bills I pay via check, like the yearly pool membership, that I can just use Simple to send out.
I've been pretty happy to not have a check book. Especially after I had a $45 check I sent someone that got stolen from their mailbox and cashed for around $2,000 each, twice at different branches of my bank. Thankfully, I noticed within a day or two, and it was only a big hassle.