If it is a coin with a lot of ups and downs, then you cannot invest in it. But it will be good to make money from it thru trading. Bitcoin will still be the best online investment because it have shown great potential and the price is annually increasing.
I agree after a huge fall last 2014, even though Bitcoin have not recovered yet from that $1200 price way back 2013, it show a great potential. After it goes down to sub $200, bitcoin is now gaining its ground and almost 63% of the price value had been recovered from that $1200. Just a couple more months and I think those people who bought at $1200 can recover their investment in bitcoin.