I'm going to go out on a ledge here and say that seahorses aren't necessarily a bad choice for a beginner. You need to do lots of reading and research. My fish saltwater fish was sort of seahorses. When I was able to add fish to my first saltwater aquarium, I put in my clown goby, became comfortable with water chemistry, water changes, maintence, then I got my first pair of SH.
They do need a lower flow than your regular marine tank. I have a 29 gallon setup with a HOT Magnum filter, and my horses did great with that amount of flow. You also want to make sure there are lots of places for the seahorses to hitch to.
The key to raising seahorses is to get captive BRED seahorses (not captive raised). These are less likely to be exposed to disease and have weakened immune systems. They also eat frozen food without fail. Their diet consists mostly of frozen mysis, which most people feed 2-3 times every day. They have a different digestive system then other fish, and cannot go without food for more than two or three days. Quite a few SH keepers like to fast their seahorses one day a week. Sometimes I skipped a feeding, other weeks I couldn't say no to four snouts looking in their feeding dish, waiting for the food to magically appear. If the seahorses do become sick, and do not eat after two or three days, owners have to make a tough decision. They need to decide whether or not to tube feed the horse. If seahorses go too long without food, their digestive system will completely shut down, and never start again.
As for good beginner horses, reidi, erectus, and kuda are all considered good starters. A favorite setup is a 29 gallon with two or four horses (preferably 1 male and 1 female, or 2 males and 2 females). Seahorses are social animals, and they do not do as well if a single animal is kept in a tank.
Tankmates are more limited than the normal reef tank. Some people are more cautious than others when it comes to tankmates. Some pretty definate rules are - snails and most non-stinging corals are ok; large predatory fish, clams/scallops, and anenomes are never ok.
As long as you do lots of reading, research, and prepare well, I think seahorses can be ok for a newbie to saltwater. And for a newbie, it is an absolute must that the seahorses are captive bred (born in captivity). I would become familiar with diseases seahorses are prone to, how to treat them, how to tube feed a seahorse (it's harder to learn how to do it when you are in a panic because your horse hasn't eaten in two days), and have your tank completely planned before you buy anything.