1. Market cap is more 1Billion$ and it is growing.
2. Infrastructure of smart contracts (custom logic above blockchain technology) involving startups and big corporations ( Microsoft , UBS etc.)
3. New opportunities for companies wanting to use advantages of Blockchain technology in their businesses (poof of ownersip, IoT , insurance, financial derivatives...).
4. Crowdsales of digital tokens based on blockchain technology attracts large amounts of investments, for example The DAO - new type of decentralized autonomous venture fund, which token holders can decide by voting whether startup will get money or not and if it is case, system will automatically allocate the necessary amount of money to company. Today The DAO attracts more than 140M dollars in ether.
It's not just another altcoin, it brings new possibilities for business to use blockchain.
And you compare BTC and ETH charts you'll see that ETH now moves in the same direction that BTC when it starts, so i think it will rise higher.