What do you like best?
There are a lot of different elements you can use, which make creating pages a lot of fun. There are a lot of templates available, as well as several icon packs - so you can really create beautiful pages if you spend some time with the product.
What do you dislike?
All the settings are not intuitive, so there's quite a bit of a learning curve. In order to get some other plugins to work (e.g. ProgressAlly), you have to switch back and forth between the WordPress and OP interfaces, which is pretty clunky. So it's not plug-and-use.
I'm also not sure the Clubhouse is worth it for an additional $17 a month. Perhaps if you're a developer, or constantly building sites. But if you have one site you're managing, and periodically need new templates for landing & sales pages, you don't really need the membership, which they really upsell.
Finally, recently customer service has been ok, but in the past it was really hit-and-miss. I actually had to stop using my preferred affiliate plugin because they said they refused to work with OP, based on the latter's poor history of customer service. Like I said, personally I've been ok with it more recently, but it was a bit of a damper to have another company categorically refuse to create an OP-compatible plugin.
Recommendations to others considering the product
Think about how you want your site to look and function 3 years from now, and evaluate OP, as well as comparable software, accordingly.
What business problems are you solving with the product? What benefits have you realized?
I use(d) OP to create landing pages, sales pages, as well as course pages. Once I figured out how to use it, it was pretty easy. BUT, had I not had a really amazing web mistress, who could take care of the CSS and certain other tech elements, it would have been excruciating.
However, thanks to our combined efforts, we've been able to create a really beautiful course site, which the students really enjoy.