What do you like best?
SimpleDB is just like what the name says, very easy to use but so powerful tool, is a non relational DB, no SQL, if you need a place to store your data, this is one of the best ways to do it, if you are user of EC2 in amazon, you can connect them really easy, the payment options is one of the best thing, because you pay only for what you use, also there is a free tier usage, which help you to learn about the tool and test it before to buy. Is so easy to monitoring, and let you focus only on development of the app, high security level, good encryption of the data
What do you dislike?
Free tier usage is very limited, only 25hours monthly, if you do not check the limit often, maybe you will see some surprises on your credit card. But they will send you to message, before reach the free tier limit.
Recommendations to others considering the product
If you need storage, your database is non relational, and you need focus only on the development of the app, SimpleDB is what do you need, will save you time, and money, because you will pay only for what you use, so it will work for small-medium-big project.
What business problems are you solving with the product? What benefits have you realized?
I use it to store data from server games, because is cheaper than EC2, so i mix Ec2 with SimpleDB, and i pay only for what i use. Is very useful to develop API, very low latency for querys and requests.