I had bought Emailit a couple months ago for transactional emails. It already worked great and now it has improved a lot with the new APIv2, improved documentation, webhooks, templates and inbound emails.
The only issues I had were when I faced some security protections and the support was super fast and helpful and unblocked me in the hour.
When I bought Emailit, my most requested feature was templates as it's so much easier to choose a template and a couple variables than send the all html code of your email through the API. Now they've done 95% of the work: templates are there, you can design them from scratch or from a model... but you can't duplicate them. It makes it basically unusable for me at this point because you have to repeat the whole creation process for each new template instead of just duplicating and adapting one design. They've done all the hard work so I guess they will cross the finish line anytime soon.
I made a couple feature requests like this for UX improvements. It's already a solid product with all the core functionality built in and it will be perfect once they make it all a little bit easier to use.