Simon Brown always says that before you buy any stock, you should clearly be able to give three reasons why you want to buy the stock, and be prepared to stay in the trade for as long as those conditions are valid.
If you can give three compelling reasons, and there are no cautionary announcements on the stock, sure, go ahead and buy the stock. However, with any penny stock, it wouldn't be prudent to buy than 10% of your shares portfolio. Otherwise it's no different to gambling.