This study investigates the performance and satisfaction of three virtual keyboards of different tablet devices. These devices were chosen to be representative of commonly used tablet operating systems (iOS, Windows, Android) in order to determine whose design solution was better conform the usability requirements of users. Twelve participants provided anthropometric measurements and they were asked to type predetermined Turkish texts in a web based application with these three different keyboards after a short trial. Typing performance, workload and participants' satisfaction were evaluated. Results indicated that, users performed better and satisfied more with an iOS tablet since they could realize the characters more comfortably due to its size and layout. On the other hand they did not thought of it useful due to the workload caused by different keyboard modes required. Meanwhile, users' performance and satisfaction was also high on windows tablet although it was smaller in size because it required fewer modes. In addition it was revealed that age and thumb sizes affected the performance and increased the error frequency. Designers must consider the required physical and cognitive effort as well as the sizes of the virtual keyboards.