Bitcoin price increases and decreases very quickly, so it is not always suitable for short-term and day-trading. It would be more suitable and safe, if you invest for long-term.
That doesn't quite line up really well though. Day traders make profit from these daily fluctuations so if btc does just that, then it should be good for day trading. The thing is it's not. Significant btc movement often happen over a period of time so it's hard to day trade with it.