I wouldn't recommend CryEngine to anybody, having known people who worked for Crytek.

Can you tell any 'tellable' explanations about this ? Is the API/SDK/code bad in some ways ? Code spaghetti maybe ?

I would recommend downloading the Lumberyard Engine from Amazon* ( see what some of the CryEngine code looks like. Lumberayrd is based on a recent version of CryEngine but has also been modified by Amazon as well. The download contains the source code for the entire engine, hence how it provides a view into what some of the CryEngine code looks like.

* disclaimer, I work for Amazon and on the Lumberyard Engine but what I write is my personal opinion and does not represent Amazon in any way, shape, or form. :)