I think it's great.
1. You have 5 licenses so you can install the full suite on up to 5 PCs without running into any issues. You can manage these licenses from office.com, say if you had already used up 5 and needed to revoke a license from a PC so you could use it on another.
2. Yes. It is a full blown local install.
3. It works perfectly fine offline. After a month or so it may start giving you reminders that it needs internet access to verify your license but it'll go a very long time before it actually cuts off functionality. For example, my Office 365 subscription ended May 25th and it allowed me to go almost a full 2 months before it actually stopped working.
4. The web app is just browser based version, which I find is "good enough". It's certainly better than Google Docs or any other Office-like web app in my opinion.
5. I'm unsure about the OS X side of things as I've never used it.
6. From reviews I've read people seem to really like the iOS apps. There is also no limit on the number of devices you can use the mobile apps on with your subscription. They state the limit is 10, but they have said there isn't actually a technical limit and they won't prevent you from using more.
7. I plan to renew my subscription, I think it is entirely worth it especially given all the value adds such as:
5 licenses for the full blown suite to be installed simultaneously on different computers
The OneDrive storage which I believe is now 1TB
The Skype 60 minutes per month
The ability to use the iOS/tablet apps on as many devices as you want
And that you are entitled to new versions without additional costs
Edit: You also get Office on Demand (accessible through the OneDrive site by right-clicking a document there and selecting "Open in Word"/Excel/PowerPoint/etc which allows you to stream a copy of Office to use it without installing it. This version is a full desktop version but does not install locally to the PC and also does not require administrator privileges.)
Also if you sign up with the year long commitment then its $100/year so you save a little over $10/month.