When I purchased Inbox and logged in the first time into my account, I got confused with INBOX, INBOXBrush, INBOXNotify. I needed time to find out what is what. I liked though. I'm quite picky and sometimes expect what others who have been in business for years have it. Inbox is still growing and I think they deserve our support.
Honestly, I thought to refund, but, but...after taking my time to get know how to move inside and set up a domain and add contacts, I have decided that actually, it is very good. It is not perfect, but if you start with the mailing list or even you do already have it and don't need a very specific setup, this is for you.
I wrote in other reviews about support. For me, support plays the most important part in any business. I deal with clients too and I know how much they appreciate excellent support such as instant replies or at least within a short time. INBOX team is not different in my opinion. This is where they win. Every time I asked something the answer arrived very quick (weekdays). They also listen and take into account suggestions.
They helped me with a few things immediately, so I could move forward with my setup.
I move from 2 different email marketing providers. It is not easy to get used to something new again. INBOX is not without cons. These are:

1. Cannot save own email as a template to be reused. The teamwork on it.
(temp. solution. I saved it as Newsletter and when I need it again, I reopen, duplicated and change the subject and whole text to re-use). A bit of work, but for time being is fine
2. More integrations needed:
- ThirveCart
- Convertbox (same guys as TC above)
- Convert Pro by Astra Theme ( I use it now)
- Elementor (their lead magnets templates)
- Integromat and more
3. Not possible to change text warnings before unsubscribing. Not everyone understands English. I had Japanese who unsubscribed by mistake because they did not know what is but wanted to check in the link.
(temp. solution - I use a text box at the bottom of the newsletter in which I wrote: if you don't wish to receive my emails and the newest updates, please click the link below. (something like this) At the end of the text, I added a small arrow-down icon to point to the link text "Unsubscribe"). Competitor allows changing this text as well.
4. Another user with independent logins. I know the team works on it and I do hope AS clients will get this feature without additional payment.

I may be picky but these are very basic stuff that I do believe will come sooner or later. I highly recommend giving it a try. I say again, so far so good for my needs. I like it a lot.