I might be getting an iPod touch in a week or two, so I've got a couple of questions about it beforehand. First of all, how is the battery life really like on it? I've heard people say that the battery life is not nearly what they expected, but I'm pretty sure they had wi-fi on all the time. Secondly, is it easy to turn the wi-fi off and on? I hope that it would increase the battery life only using it when needed; does it?
WiFi will definitely suck batteries as will a bright screen. But so will some applications. So there are three things you need to consider:
1. Learn to manage Wifi
Shut it off when not in use. Simple as that. Turning it on and off requires going into Settings > WiFi and tapping it off. If you have a Jailbroken device, then get the WiFiSwitch app and leave it on your Dock. A single tap toggles WiFi on or off making easy to manage.
IMPORTANT NOTE: Putting the iPod Touch in standby (by pressing the top power button once as opposed to turning it off by pressing and holding the power button and then sliding the power-off slider) DOES NOT shut off WiFi. It remains on when in standby mode, so this WILL affect how fast your battery drains. I've left WiFi on accidentally over night, and awakened to an iPod Touch with a drained battery requiring a restore. (Note that I do have OpenSSH installed, so that may have something to do with it, but all I know is that I can successfully and continuously ping my iPod Touch when it is "sleeping".)
2. Determine what level of brightness you really need
For "lighted room" conditions, I keep the brightness at about 1/8" from the left of the brightness slider. In dim or dark room conditions, I have it down even further. I personally don't like the scale apple uses, because for me, the higher brightness positions are simply too bright, and it's sometimes difficult to manage the brightness at the low end of the scale. I almost wish they would have implemented the "roller" UI widget instead of the slider. As for the Auto-Brightness, I've played with it, but haven't had much success. I'm using a Belkin Silicone skin with a cutout for the light sensor, but it still may be covering the sensor.
3. If you are using a Jailbroken device, some applications can really drain the battery, simply because they use lots of CPU power. An example of this is the EvolutionRGB game. I was REALLY bored one morning, and specnt about an hour just mesmerized by it, and I noticed that the battery had drained about 50%. But that is probably a huge exception. You don't need to worry about most apps, as they are mostly static.
Finally, are people still having issues with the screen quality? I won't have too many movies on the touch, but I would like them to look good if and when I do.
I'm more than satisfied with screen quality. I've used many PalmOS PDAs over the years, and the iPod Touch screen excels on all counts in my opinion.