Performance wise, it is very good. Low latency when accessing it from Sweden and fairly decent bandwidth. Cost-wise, I'm not so sure. Without an instance reservation, the monthly cost is about $79 excluding bandwidth costs. But that's when paying on-demand so it wouldn't be a fair comparision to dedicated or VPS hosting where you have to subscribe to the service.
If you sign up for a European reserved small instance for a three year period, you get a monthly cost of $19.5: (350 + 0.04 * 24 * 365) / (3 * 12). That's not to bad when you take into account that one ec2 instance is more like a dedicated server than a VPS. But signing up for a three year lease is a very long time. The monthly cost for the one year plan is $48 which is much less cost competetive.
From everything I've read, it seems that Amazon EC2 underperforms when compared to other hosting options. On the other hand, the job market seem to favor ec2 experience so it might be worth going with it just for that reason alone.