I've found bolt to be completely awesome. I've made 5 or 6 sites with it, made a couple utility extensions, and used the local extension system to do stuff like custom search, a basic shopping cart, and a custom data export feature. Aside from the technology stuff it's got a positive community, good documentation, and active user base on the forum and chat.
Though I guess that is really a composer issue, the inability to not use something like curl when allow_url_fopen wasn't available seems insane to me. allow_url_fopen is not a great thing to have enabled in production.