So this is my thoughts after using the public beta. I have an iPhone 6s+. I will mention, i attempted to put feedback through the app on the phone however it wouldn't work.
To be honest, this build is less of a beta and more an Alpha based on the usage of the phone.
There are numerous visual glitches (which considering the lack of front facing changes is surprising), the multi-tasking has glitches where apps won't close and the animation left to right barely works, screens with disappear off the screen showing half black, the feedback app didn't work for me), the OS at this point is an absolute mess of a system. Obviously they'll fix it for launch, but damn.. i've been using iOS betas since 7 and this is easily the worst i've ever experienced.
One note for people, downgrading is a nightmare. If you attempt to go down to 10.3.2 you will end up in a permanant restore loop. You need to download the latest beta 10.3.3 (4 when i fixed my phone last night) and you can download the firmware from apple (google, you'll find it). One mention, on iTunes on window, hold the shift key on 'update' and will let you select the ipsw file.
I don't mention this to slam the system, but to warn people so they don't suffer the same challenges i did.