One of the main problem is the transaction speed and the confirmation problem, but my problem with bitcoin is too many scamming in bitcoin, a lot of people using bitcoin in a wrong way
Yeah, sometimes it very long and boring and better to go to sleep, but about scammers it's only your fault if you was scammed, usually scammers are bad.
I will say that confirmation timing is not much higher once you get three confirmations you get the bitcoins to your wallet ,
and if you remain alert and will have knowledge about every field relating bitcoin then no one will be able to scam you.