I use iRhino almost daily. It has really been helpful to show my designs around the office and in meetings. Its most helpful to get design suggestions or just to show people what I have been working on.
Using Version 2.1.8
I do have a few suggestions…
Dropbox view doc and sign out buttons need to be spaced apart. I am constantly hitting the sign out button by mistake. With the two step verification I have to sign in again an have to wait for a new code to sign in. While i have a room full of people waiting on me, This can be very annoying during a meeting. Could we move the sign out button to the bottom of the page? My fat fingers would thank you 
Also can iRhino remember the last dropbox folder I was in. It would be helpful so I don’t have to navigate all the same folders to the desired project folder each time I want to load a file. My folder organization of my dropbox folder is extensive. It would save time if picked up where I last left off to load additional files.
When I am loading a new file I get “This model is only wireframes and can not be displayed. Save model in…” the dialog box cuts the rest of the message off. I’m not sure what it means or what to do because the dialog is cut short. I end up just deleting it opening it up in mac rhino and doing a save as and adding it to iRhino again. Sometimes it works Sometimes it takes a few times for it to work. I am not sure what is going on here.
I also get the dialog box that the file not available or inaccessible. These are files that I have already loaded and viewed earlier. Now, I think it because i had loaded the same file twice and deleted the duplicate file. I am thinking that by deleting the dup file, this is somehow deleting both loading file because they are named the same. This icon of the original file is still there, but is inaccessible.
Question, why am I able to load the exact same file multiple of times. I think this maybe causing problems. I can reproduce this error 100% of the time.
If am viewing my model and click on the layers button to see what layers I have turned on and then click on the scene without clicking done. The “Models” button is grayed out. I have to return to the top menu bar and click any of the buttons to get the “Models” button back to return to the main screen.
I know different display modes have already been suggested, But I would also like to give that suggestion another bump 
I would love to use pen display mode and display dimension lines.
My customers would not have to ask the tall something was and I would not have to refer back to the original 3dm file or a print out. 
Cheers