Even if I increase frequency eg with 25Gh/s I will earn 0.01BTC in 2 years...
Please tell me if I am wrong.
Small USB stick miners, like this one, are more for getting started in the bitcoin mining game. They are mostly a learning tool, but also a way for you to join the community. That said, the miners do contribute to the distributed nature of the bitcoin network. Unless you are solo mining and find a block, which is not impossible, just highly improbable, they will not return your "investment."
Yes, they require a little hands on effort to get going; a nice entry step into learning [a lot] more about bitcoin mining.
As far as how it ranks in the theoretical BTC/day space, and a glance at other miners, visit this miners table:
http://mining.tipsternet.com/miner.html