I personally would recommend the new version. Simply for these reasons:
The device will be supported longer. A good example is Siri will be made available for 3rd Gen and not iPad2. That is just the tip of the iceberg in the next couple of years.
If you don't plan on upgrading, get something that will have more longevity. The retina screen is very lovely and definitely a pleasure to look at.
Heat is a non issue on mine and I do play some games on it.
The battery does not take me the duration of a whole night to charge. For myself I plug it in on Saturday or Sunday and get it later in the afternoon or evening if I find myself needing it. The battery lasts me more than a full week just surfing websites, news readers and Zynga poker every night for at least an hour or so.