In those instances the time it takes to fail reading your finger because it's dirty, you could have used the pattern unlock alternative. (Rather than long password).
Don't get me wrong, the Iris scanner is a nice feature and it's good it works, but it fundamentally is a solution that is looking for a problem over the existing technology already available.
I get the excitement for the Note 7, it's a fantastic looking device, but it does seem you lot are getting carried away in the launch excitement by the least interesting new feature rather than some of the genuinely great stuff that make the Note 7 a fab device.
I disagree on the usefulness there. The fingerprint reader is hit or miss when wet or dirty, sometimes it works and sometimes it doesn't, so I always try it first and actually let it scan a couple of times before I give up and enter my password, which is a 10 digit password combination of letters and numbers. And if the phone is wet (it is water resistant and I've used the edge in the pool and in the rain) even that is a pain because the water droplets cause false touches all over the place. I could use the pattern unlock, but that is less secure and I can only choose one.
But now I'll have another option to just hold it up to scan my eyes. I don't wear glasses or contacts so that won't be a problem. The finger print reader will still be my go to, but I like that I'll be able to fall back to the iris scan instead of then having to put my password in.
Of course all this is dependent on how well it actually works in the real world, but from the videos I've seen they seem to have implemented it well.
Edit:
I do get the excitement for the Note 7, it's a fantastic looking device, but honestly it does seem you lot are getting carried away (like a Mexican wave) in the launch excitement by perhaps the least interesting new feature rather than some of the genuinely great stuff that make the Note 7 a fab device. (Such as the 4096 levels of pressure sensitivity which is amazing on a mobile device for stylus users, after all it's called 'Note' for a reason)
I honestly see the IRIS scanner on the same level as the HR Sensor, and I remember these exact same arguments about its usefulness when Samsung began using them and now it's resigned to that feature most users never-ever-utilise and is never talked about anymore.
Saw this after my initial response. I'm not putting the iris scanner at the top of the list of why I'm excited about the phone, the design is what I'm excited about. It is a unique feature that I've never tried before so there is some excitement on trying it out, and hey if it works well I can see some use cases for it, so I disagree on its usefulness.
As for the spen, I was actually a bit disappointed in it. The new features seem cool, but I was really hoping for tilt like on my apple pencil. And the thinner tip actually made it more awkward for me to use than my past notes. Again will have to use without those pesky security attachments, but first impressions I was disappointed in the hardware of the new spen (software is a different matter, that I actually liked).