They are very slow, but they can be ok if you get them for fair price, which is really hard. Paying more than 1$ for a USB miner is waste of money. Note that you will need at least 100 of them to get some BTC out of it.
I am not familiar with those. What's the deal with cooling them and where do you plug 100 pieces? Some special device? How much does it cost?
You need USB hub, where you can plug like 10 of those in at least and cooling is not big problem, since you can put Aluminum cooler on it, but you have to consider slow speed. On this difficulty you are getting less than 0.01$ per day out of one 330MH USB block erupter. Consider Buying Antminer rather, but be carefull with price. Make calculations first.