This is a dish I will order frequently when I am having one of those "I don't know what to eat today" days. There is a place just down the street from my house that makes this dish quickly and cheaply and I probably eat there a couple times a week.
There are a ton of ways that this dish can be modified and well, if you go to the wrong place than can quite easily spice you out of the market - so it is important to specify how spicy you like your food. Normally, a Thai chef will realize that (generally speaking) foreigners do not like their food as spicy as Thais but if in doubt just say "mai pet" if you can't handle spicy.
There is a common misconception that Thai food is healthy and this is definitely not true for this dish but a lot depends on what kind of diet you are going for. For one thing, rice is one of the worst things you can consume if you are on a low carb diet and if it weren't for my current exercise regimen I wouldn't be eating this. The condensed coconut milk that goes into this dish is also extremely high in fat so you may want to watch out for that.
You can get it without the coconut milk but then the flavor changes to something that isn't really similar at all.
Red curry is extremely common in dishes in Thailand and it is one of my favorites. I find that the coconut milk reduces the spice significantly but at the cost of a billion calories or something. Whatever. Live a little! Right?
enlarged to show texture - just like they do with cereal!
Some places will leave all the skin and gilly-bobbers on the prawns and I would much prefer they don't do that because it just makes a lot of work and well, i find the heads to be gross. It is my understanding that a lot of people don't mind that and if this is you, then go for it! I don't really think you have a choice at most places however. My place just removes all but the tails by default.
This dish costs about $2 - $3 and is what I consider to be a great value. It can be obtained for a bit less at one of the street food stalls but as far as eating in a restaurant is concerned, this is about how much you can expect to spend on the bottom end.