Consider this line as intro.
Large Volume exists on centralized exchanges
Yesterday, I was trying to do arbitrage with Steem Dollars when I saw there was huge difference between hitbtc, poloniex and bittrex prices.
I was like hell yeah, easy money! Then when I checked on poloniex and hitbtc - SBD wallets were under maintenance!?
When you see volume — bittrex, poloniex and hitbtc has the largest volume. Whereas decentralized exchange openledger has only few thousand worth volume.
Takes much time to show deposits
I did BTC deposit yesterday on bittrex, even though on Blockchain.info transaction had already 3 confirmations while Bittrex was showing up 1/2.
Creating Accounts on different exchanges for different coins
For centralized exchanges we have to wait until that exchange decides to add that particular coin/token (and that listing costs 5-15 BTC) while on decentralized exchanges for example, etherdelta you can open your market just by using that particular token's contract address.
Hefty Fees
Exchange fee+Network fee. Livecoin takes 0.01 eth fees for every ether withdrawal while if I withdraw ethereum from etherdelta it costs me some cents.
HelpDesk
Good luck on getting replies from so called Helpdesk of centralized exchanges. Oh wait.. you will get surely get reply but from bot, hah!
Verification
Bitch please, cryptocurrencies are supposed to be anonymous.