I've tried version 1.5.1 for some time now. I had tried Inbox when it first came out and did not find it matched my workflow at the time and I didn't check it again until version 1.5.1.
My first impression was very good. This is an application that seems to implement GTD with a method to collect from various places, like emails, folders, event from calendars, etc. Which is a good way to force you to consider all your virtual inboxes. It then tries to help you assess each item and process it the GTD way by thinking about the "actionnability" of each item, etc.
The problem is in the implementation. It's a good idea poorly implemented. For instance collecting emails is a great idea, but you have to be able to configure it in a way that you don't end up with all the emails that are tagged as spam and are in the spam folder. And calendar events are a good idea, but even though you want to display calendar events for your co-workers on your calendar application, you don't want to have to process them! And again this is not configurable.
Another example of the poor implementation is the process dialog cannot be resized, which makes collected items with a long description unreadable (you have to put the cursor in the small portion of the text displayed and scroll with the arrows to be able to read the whole text, the window doesn't adjust to the size of the text and cannot be resized).
The new web site and the displayed screenshots of version 2.0 made me very enthusiastic about this program and I wanted to invest myself into it. I thought that version 2 would certainly fix the interface shortcomings of this 1.5.1 version and smooth everything out.
I bought the mobile version for iPhone with the hope it would be able to sync with version 1.5.1. It doesn't.
Trying to reach the developer for help with the sync was the first sign of a problem : it took them forever to answer my bug report. And the answer was not satisfactory. They clearly didn't read my report and answered first about the iPad version (when my report clearly stated the iPhone version). Another long delay after I replied I was talking about the iPhone version and they replied that it didn't work sometimes for the iPhone version but that version 2 should fix that.
Fine I can wait a little, but I need syncing with my iPhone.
Then the wait starts. After a while you try to contact them to know when to hope for 2.0. No answer. You start to look around, you find the Facebook page where they announced version 2.0 more than a year ago, you ask your question there. No answer in weeks. You post a question on the comment section of their web site and it's in "approbation by a moderator" for weeks and then it disappears without any answer. So after still some time you start looking around and find these reviews on Macupdate and you realize that you're not alone. This is nothing new. This company has a history of procrastination.
I won't invest my time into vaporware. I think this could be a great implementation of the GTD system, but really get your act together Midnight Beep!