Performance wise MediaTek's processors are solid performing. Their extra core processors enable intensive and heavy task performing and they are very good at multi-tasking. Snapdragon has even better performance in multi-tasking, handling heavy and intensive tasks and gaming.

Why is MediaTek not good?

The problem is manufacturer are using old and low end processor's of Mediatek. Most common processor used by manufacturer from Mediatek is the quad-core MT6737, it was made 2 or 3 years ago and that too is low end processor from Mediatek.

Is MediaTek worth buying?

Are smartphones made with MediaTek chipsets worth buying? Well, absolutely. With Oppo f3, Lenovo A7000 are live examples of the success of the company. It has amazing companionship with best mid-range mobile phones which are made smart due to it.