A lot of people are discouraged with the battery 'problems'. Here's what I experienced/found:
After installing and trying out several apps with my new DInc, I was experiencing a battery drain problem- I was only getting 5-7 hours on a full charge- with minimal usage. I installed taskiller, and started shutting down apps when I knew I was done using my phone for a while. Guess what- I now could go all day and only use half the battery with moderate usage. The majority of my problem was a few apps, especially Bubble (level), that drained the battery rapidly.
Now not everyone has this app, but it is a good example that there is no single solution: everyone's usage is different. Maybe you have another app that is draining. Maybe it is a widget that is constantly syncing.
You just need to experiment, and through process of elimination- determine what your battery culprit is, and make the needed adjustments.
Remember too, before complaining about poor battery design: This is more than a cell phone. It is a computer! You wouldn't expect to run a laptop all day on a single charge (how big a battery does that have?!) There are certainly faulty batteries, DIncs, and SD cards, that can cause battery drain, but they are the exception rather than the rule.
The key: Power Management on Your part!