This is an exchange founded in 2011. It is a cryptocurrency spot exchange that also offer future contracts.
It based in US and also under the strict regulations of US regulatory bodies. May be that's why it doesn't trade too many Currencies, only 20 cryptocurrency are on the platform.
It has many advanced features that makes it not suitable for newbies rather the professional traders can easily find their ways to through the platform because.
Sure American based traders will enjoy it more for it offers multiple tradea opportunity.
This exchange restrict many countries from using the exchange also it set limit on withdrawal but no limit on deposit even for traders without know your client certificate.
It also offer dark pool , an order book that allow traders to trade with annonymity.
All in all I think kraken is good and secure only that it is not open to traderz from many other countries.