For me, probably the transaction confirmation times. That is one the biggest wow or attractive factors with bitcoin for myself personally. It is getting too long.
Yep nowadays it's getting very slow, i remember to transact in 10 min a while ago, now it takes 50 minutes.
It would be nice for a faster confirm time like 5-6 minutes.
Im experiencing it too like in my previous transactions. Im using web wallet most of the time (Coinbase and our local wallet exchange), and transaction time really sucks but in the past I don't have a experience like that using web wallets most of the time.