+ Watching DVDs requires separate playback software
This appears to be the case. I can't get Win10 to play a DVD with WMP.
I expect this is because DVD decoder software requires royalties to the DVD Forum for commercial software, and Microsoft decided not to include it with prerelease versions. Considering most people who are "serious" about watching DVDs either watch it using other devices or they use other software anyway, I don't think this is a problem even if it isn't temporary for the pre-release. (I seem to recall The Win7 Beta couldn't play DVDs either)
+ Windows 7 desktop gadgets will be removed ainstalling Windows 10.
Well, considering they were an unfixable (by design) remote exploit, I hardly see this as a negative, myself. Let's see, have a bunch of silly eye-candy gadgets on my desktop, or be susceptible to remote execution exploits that could allow software to take over my PC. I think that choice is pretty obvious.
+ If you have a USB floppy drive, you will need to download the latest driver
This is untrue. My USB Floppy drive works when I plug it in without downloading or installing anything.