What does the software or service do well? My company switched to WP Engine after looking for a solution to insecure self-hosted WordPress sites that kept getting hacked and infected. WP Engine has been a breath of fresh air ever since. Their platform makes it really easy to set up a new site and get building and since their product is WordPress and nothing else, there's lots of great expert support for you, too. Even on a lower/basic plan, the tech support is AMAZING. Some services leave me dreading when I realize I have to pick up the phone or start up a support chat. WP Engine support is so good and the staff are so friendly; I get my questions answered and have fun along the way.
What does the software or service not do well? I think sometimes the tech support assumes I'm an expert at a lot of back-end stuff that involves code or understanding of servers and so I need to ask them to repeat steps in detail... but they're also super patient and if I'm ever stuck or unable to do something, they're usually pretty good at just taking the wheel and handling it for me. One challenge I face is ensuring my domains are mapped correctly and I'm getting my SSL lock on my sites.
What do you wish you had known about the software or service before using? I can't think of specifics but I definitely learn something new from time to time; especially when working with tech support. Even just this month I learned that I could edit my htaccess file to help ensure my SSL certificates are authenticated properly. Getting access to staging environments is also a useful tip I learned so that I can make changes to a site without affecting the live version... and then just push the new version live when I'm ready.