When reading the reviews, i was really wondering what kind of shitty product this must be. But, after stacking four codes, I must say that everything seems to work decently. I haven't experienced any bugs compared to other mail automation platforms that I've used.
Although I have only ran some test campaigns, I must say that the interface is very intuitive and all the needed options are there. Concerning email warm-up, this is and stays a great mimick, no one really knows if it works and what not.
I believe that as long as you do small-scale, highly personalised, outreach, that this seems like a really great tool. I have just activated one of my clients through Reachinbox and will see where it takes us. The test campaign results were decent and replies were fetched accordingly (using SMTP/IMAP protocols). To me, that, along with deliverability, is all that counts.
Blasting 10.000s of emails will indeed not work, but that wouldn't work with any tool...
A small improvement point that i saw until now: White Labeling -> there is a lot of Reachinbox promotion still there (login, de demo stepper when first signing up, the header of the tab, etc). Would be great if this could be further improved.