SAP HR is easy to learn! But a candidate should have atleast 2 years of Exp. in the Domain (i.e. HR Field). If that being the case SAP HR Can be learnt. The Other important thing is SAP is the emerging field so need not worry about the openings.
There are lots in many large and emerging companies, the amount of effort you take in learning is what matters. No one can be an expert in SAP, but one can only benchmark the best. So learning of SAP doesn't ends once you get the job.
But for getting job there are few predefined expected question, which one need to concentrate for initial entry. After getting job, for career growth one can go to the deeper extent. If any further queries on SAP.
Feel Free Contacting me, Ready to share my limited knowledge. Gayaz : 9884272786.