Everybody is talking about great things they liked about the V10. We all know how great this phone is but is there anything you don't like about the V10?
The speaker. That's pretty much it.
Other have mentioned the primary things...battery is not great but it's OK for a modern smart phone. About comparable to the Sammy S6. The no LED thing is just weird, but I understand why with the second screen.
To add a couple of quirks, the two cameras on the front in certain light look like notification icons when you first glance at the phone and so I find myself thinking I have a message when I don't (again, see the no LED thing). I have the black on black so perhaps other colors don't do this. Also, related to the second screen, when watching video in landscape mode, the second screen in dark, which causes weird chunkiness to the screen as there are two right angles involved.
I also wish it had the fast launch camera shortcut that the S6 has. I liked double clicking on the home button to launch the camera and wish all phones had a similar short cut.
EDIT: Forgot my primary gripe. They HAVE to open up the fingerprint reader to third parties so that it can be used as security. Not being able to open LastPass with my fingerprint sucks badly after doing that for a year with Samsung.
But overall, I think it's a great phone. The removable battery and SD card is great and I feel very comfortable without a case.