I just installed it to a separate partition to see what my opinion was before I made a decision to upgrade my Windows 7. Going into it I was of the opinion that I was going to completely hate it much as I hated 8, but I was plesantly surprised to find it rather enjoyable. This morning I booted into Windows 10 without really thinking much about it, so that's a good sign I guess. I tried doing the exact same things using both a windows account and a regular desktop account without issues. There may be some with regards to the store but I haven't even looked at that yet.. and honestly probably won't.
There are a few things I don't like so far - particularly the fact I can't add a custom color to the themes as I could in my Windows 7. This isn't a game changer but just something small I wish was present. The colors I was interested in were slightly off of what I really wanted, so I'll just stuck with the default color for now. I also wish I had the ability to change the default system font (which was removed starting in Win 8 I read?). Again something small that doesn't matter much I suppose. As well there were a few games that I wasn't able to get working but this probably comes mostly from the fact I was running them off the other drive. I am sure if I reinstalled them or upgraded my Windows 7 this would be fixed.
With the title bar coloration posted earlier I do wish this could be changed. I think this mostly stems from the fact I am used to a discoloration =[ Maybe this will be fixed in the service update they said comes next month? I mean as time goes on it isn't quite as bad but I would just like it a tint darker.
As far as configuring settings like Cortana and what not that was basically straight forward. I disabled her as I don't really care about that feature or a voice search in general on any device. I am glad that you can optionally disable it if you'd like as opposed to something which was always on. I just know I won't use it but I am not upset it was added in. We all have differing opinions about a feature and that's perfectly fine. I also disabled the internet search feature in the bottom left as it made it rather laggy when I was searching for a specific program I wanted. The configuration process could be.. er.. streamlined by placing all the settings in the same location. It was rather annoying having to travel all over the place just to adjust something.
Just out of curiosity does anyone know what happens if your Windows account credentials are stolen? I was just thinking about this this morning and it makes me feel like on the off chance that did occur you would be completely locked out of your computer.