What are the major benefits of opting for mobile phones with double SIM (2 cards) solution except of course, cost advantage?
The comfort of using one handset instead of using two phones for every card is one aspect. As well as time effective solution as you need to take care only of one handset (charging, servicing, and installing additional apps). Dual SIM mobile phones give you a chance to store more contact information on two SIM cards which will be of great use for users keeping all contact information of their friends in phone contact list (for example: the popular smartphone Lenovo S920).
Moreover, double SIM handsets are the best solution for travelers who often visit areas of poor connectivity, as chances are rather low that both mobile carriers will have poor coverage in the region, thus you will still be connected with your dual SIM phone as one of the cards may still be available.
However opting for a double SIM mobile phone you should keep in mind some disadvantages such as: Low battery life - dual SIM smartphones commonly bite into battery life severely. So you should take care of a timely phone charging to keep in touch.
There is the idea that double SIM phones are poorly equipped and feature fewer options than single SIM mobile handsets. However experience has proven that every user can find an optimum dual SIM solution meeting all needs and fancies.