There has been a ton of talk about battery life with ICS, and while I am NOT an expert on the subject, I can say from personal experience that it all depends on how the phone is set up. I had a Droid 2 before I got a Razr Maxx, and I got pretty good battery life with the D2, even though I had it over-clocked. The D2 lasted me almost two years before I went to the Razr Maxx. You have to remember if the phone is on and in use, even if the screen is off, it's using battery. EVERY app and function in the phone uses battery.
While this is simply MY personal preference with the setup on MY phone, there are things you can do to take care of the battery and make the phone use less battery. Everyone uses their phone for different things, and in different ways, so as the old saying goes, "your mileage may vary".
First of all, my phone IS rooted, and yes, I tether my laptop. Take THAT Big Red.
The CPU in the Razr Maxx is listed as 1.2 MHZ, with 1 GB of RAM. That's blazing fast for a phone. But that fast dual-core CPU uses battery. So after much research and reading, I UNDER-clocked my phone. (Yes the phone HAS to be rooted to do this, as far as I know, I may be wrong) I use "SetCPU", which is available in the store. I set up "profiles" in SetCPU to under-clock, using less CPU, which in turn uses less battery. If my screen is on, it only uses 1000 MHZ, rather than 1200. If my screen is off, and the phone is not being used, it uses only 300 MHZ. If I turn the screen on to use the phone, it automatically kicks on to use the 1000 MHZ I have it set for. And as the battery drains, it uses even less CPU and battery when the battery level gets to 80%, 60%, 40%, and 20%. Essentially, the more the battery drains, the less CPU it uses. The only noticeable difference in performance is when the phone gets to 20% and it's using minimal CPU, it's just a tad bit slower.
But there are other things you can do to keep the battery from draining too fast, and get the most out of it.
REMEMBER, these are things I did in MY phone, everyone uses their phone differently, and everyone has different preferences. If you are watching movies and Youtube videos all day long, your battery is going to drain a little quicker no matter what.
These are things I did to save battery:
1) I turn off all Wifi, and GPS, and "Location Services" ... if I need it, I turn it on. If an app requires it, it will tell you, and give you the option to turn it on. I leave it off until I need it ... otherwise, it drains battery.
2) I have 95 apps that I downloaded in my phone. NONE of those apps "auto update" ... if I get a notification for "Updates Available", I do it when I am ready.
3) I keep the screen brightness down, roughly 25% of the brightest level.
4) I turn off notifications on everything. News, weather, and anything else that sends a notification for anything, uses battery to do so.
5) My screen turns off after 1 minute of inactivity. If I set the phone down, it "sleeps" after 1 minute.
6) I also "Freeze" all of the bloatware in the phone using Titanium Backup, you can easily find a list of what is safe to freeze with a search of this forum.
Again, everyone uses their phone differently. These are just things I DID on MY phone, and so far I am quite happy with my battery life, as you can see in the screenshot. The screenshot was taken after 24 hours of phone calls, surfing, Facebook, Twitter, texting, and a couple Youtube videos. There was about 6 hours of sleeping in there too.
Now as far as charging the battery, I am sure "FoxKat" or one of our other resident experts on the subject can weigh in on what to do with charging to optimize battery life.
If you do it right, you CAN get good life out of the battery. A phone battery is like a woman, or your teeth. If you don't take care of them, they will leave you.