Usability is one of important aspect that supposed to be considered in designing easier, effective, efficient smartphone. This study aims to determine the usability criteria that affect the ease of use in touchscreen smartphone, using a case study on two brands of smartphones that has the biggest handheld market share, which is iPhone and Samsung, with Indonesian people with productive age range (18-35 years). Furthermore, through eye-tracking research results are expected to provide inputs related to touchscreen smartphone interface with usability design. There are three approaches used in this study, which are performance measurement, subjective measurement with modifications of USE (Usefulness, Satisfaction, and Ease of Use) questionnaires, and eye-tracking. On the approach of performance measurement will be measured five usability criteria, namely understandability, operability, frustration, efficiency, and learnability. The subjective approach used to assess the satisfaction of smartphone users about the five usability criteria. Correlation between subjective approach and performance measurement approach will be tested using Pearson correlation test. Meanwhile, the eye-tracking approach will be discussing the attractiveness criteria where smartphone displays are being tested.