In this study we evaluate the usability of tablet PC device, including the way the respondents perceive it. Usability of this kind of device is compared with the usability of other similar mobile devices. The Technique for Order Preferences by Similarity to an Ideal Solution (TOPSIS) is specifically implemented, and the outcomes are compared with the calculated System Usability Scale (SUS) scores. The advantage of the TOPSIS method is in its ability to identify the best alternative quickly and precisely, which is one of the most important features of SUS scale, too. [Projekat Ministarstva nauke Republike Srbije, br. 036012, No. 036022, No. 036006 and No.179002]