Personally had not had issues other then when attempting to do market sells and it not letting me so had to do do limit sales. Potentially i think they had some issues getting DDoS'd which caused some down/latency with the site a bit but its NOTHING compared to Kracken......shiver

Kracken cost me quite a bit being down in critical moments and only allowing a certain amount to be transferred out when another exchange was supporting a fork.....thus i missed out on free money....

That being said Kraken is more on my bad list, whereas Hitbtc i havnt had too many issues with. What other exchange are you looking at?