Yes it worth it particularly if you are on a tight budget. And software updates are available for mtk devices as well.My xolo Q800 recently got an upgrade from 4.1 to 4.2. Micomax devices also gets their updates.
I have a xolo q800 (quad core,1gb ram,8mp camera and sensors like gyro, compass etc) got just under 10k Indian currency which can beat all other branded devices under this price tag in terms of performance. 1080p videos and most of the common games are running smooth. All thanks goes to the mediatek chip set.