Thai food rocks! I really only first started eating it about 4-5 years ago but it is definitely one of my favourite styles of food now. I think of Thai food as being very clean. By that I mean that you don't feel sick and greasy after eating it like you can after eating Chinese food. It tends to be spicy, although you can easily get a made milder if that's what you prefer.
Compared to Indian food, Thai food tend to be a 'hot' hot, while Indian tends to be a 'sour' hot. It sounds quite weird but I find that I can deal with even the really hot Thai spices. They chilli tend to be hot and spicy from the start (which I like) but at worst it just make my nose run and my mouth numb. Indian spices on the other hand seem to build as you eat the meal. The don't really seem that hot when you are eating a mouthful, but I eventually get to a stage where the heat from the spices makes me not want to eat any more. It's quite hard to explain but that's the best I can describe how it feels.
I personally love having my Thai dishes with rice but a lot of people like the noodle dishes (like Pad Thai). I love eating the rice after it has soaked up all the lovely juices of the dish. The rice also helps to take a bit of the edge of the spiciness.
In Australia, I have found that Thai food has red onion in it, rather than the more common white or brown onion. I don't know if this is just a regional thing of if Thai food normally has red onion in it. Spring onion is also common though (usually in addition to the red onion). If you are having Thai food in a restaurant, you can generally just ask for it not to be included in your dish. Of course it may depend on the restaurant, but the place I go to isn't by any means upmarket and it will still leave out or include specific ingredients on request.
Olaf the Stout