Overall I like Nougat. I have an S7 and I think it did improve my phone. I noticed previously I needed to have background data restricted on my phone to get decent battery, and it still drained quite a bit while the phone wasn't in use. With the N update my battery barely drains when not on. I am able to get home and still have around 50% battery, even with some use of the phone throughout the day. Right now my battery is at 85% and it has been 5hr 38m since the last charge. Screen on time is only 22m though. Still my phone would be a lot more drained than 85% when it was still on MM. It'd probably be like 60% right now.
I don't really have an opinion on the new notifications bar. I don't really like it any more or less than I did on MM. One of my news apps was not working properly with the updated notifications and I ended up disabling Notifications from that app. I do like the pull down settings a little better, mainly just the way it looks. Also I prefer the lock screen with N. I had to use a Lock Screen App with MM because I hated the font it used. I removed the Lock Screen App from my phone once I received the N update. Also for the most part the phone seems smoother. The only time I noticed it lagging a lot was when the battery was getting low and I was using several heavy applications. I think when I haven't been overloading the phone with tasks, it has been running better than it was on MM.