What do you like best?
BBEdit has a super clean interface, support for custom languages, all the line editing, column width, margin options you'll ever need in a code editor.
I've been using BBEdit for 8 years, and it's served me well for projects in PHP, Perl, C, Unlang, HTML, JSON everything. It's nice to have a single Semi-IDE which handles everything I can throw at it.
It also support ctags which enables project wide function/variable/include autocompletion for C, which is extraordinarily useful for large projects, and makes it almost as productive as a full IDE.
What do you dislike?
Where BBEdit fails, is semantic search/replace and refactoring. You really need an editor which understands the language you're editing to be able to do that right, and BBEdit has no framework in place for this.
BBEdit have switched to the semi-subscription model of licensing, where they'll release a new major version every few years, and then get you to pay an upgrade fee to stay on a supported version.
Unfortunately the features they add with major versions really don't justify the upgrade fee.
Support from the BBEdit team has been patchy, sometimes they're brilliant, sometimes they just ignore your bug reports. Bugs that I reported in BBEdit 10 are still present in BBEdit 11 (that's a fair few years for a bug to unfixed).
Recommendations to others considering the product
Shop around and see if editors/IDEs meet your requirements.
If you're a jack of multiple trades (languages) then BBEdit is a good base editor, that offers some advanced language features, just don't expect it to do everything.
What business problems are you solving with the product? What benefits have you realized?
I contribute a significant amount of code to open source projects.
I'm primarily a software engineer, but handle documentation, and gap analysis too.
The main benefits are having a single unified interface that works pretty well, for all the different languages that may get used in a project, that's a big win in terms of productivity.