Introduction: Airbeds used to be very heavy and were cold to sleep on because the air moved around taking heat from the body. Modern airbeds are extremely lightweight and most models offer some insulation, most of all though they are the most comfortable mat because they are thicker than other mat types so the body can sink into them and get good support. Some are thicker than others, so check this out when choosing a bed, the thicker they are the more comfortable they will be.
Insulation: Some airbeds do not offer any insulation at all, they are very comfortable but the movement of air inside the chambers sucks heat from the body, making them colder to sleep on than other mats. This is not necessarily a problem for summer or three season use, remember you will still have some insulation from your sleeping bag under you. The more expensive airbeds are insulated - there are a number of ways to do this - you can glue an insulator to the inside for the baffles, you can add a layer of down to the inside of the mat, you can add reflective layers to reflect heat back to the body and you can make the air chambers small enough to prevent air movement. Some mats use a combination of these techniques to produce a mat that has a high insulation value - this can be measured and is called the 'R-Value'. A full explanation of 'R-Value' can be found HERE.
Disadvantages: So, their pack size and weight are generally smaller and lighter than self inflating mats so they are offering a much better nights sleep than any other type of mat, what is there not to like? One disadvantage is that if your airbed gets a puncture you lose both comfort and insulation - at least with a self inflating mat you still have some foam to lie on, and a closed cell foam mat can't get a puncture - so for longer trips some people may prefer closed cell foam because nothing can go wrong. Another disadvantage is price, insulated airbeds are the most expensive type of sleeping mat. The smallest and lightest is the Thermarest NeoAir, which crinkles a bit when you move around on it - some people find the sound distracting when trying to sleep. You also have to blow airbeds up - which can be a bit of a chore at the end of a long day on the mountain, though you can get very lightweight devices to pump them up.
What to look out for: