Automatic personality traits assessment (PTA) provides high-level, intelligible predictive inputs for subsequent critical downstream tasks, such as job interview recommendations and mental healthcare monitoring. In this work, we introduce a novel Multimodal Personality Traits Assessment (MuPTA) corpus. Our MuPTA corpus is unique in that it contains both spontaneous and read speech collected in the midly-resourced Russian language. We present a novel audio-visual approach for PTA that is used in order to set up baseline results on this corpus. We further analyze the impact of both spontaneous and read speech types on the PTA predictive performance. We find that for the audio modality, the PTA predictive performances on short signals are almost equal regardless of the speech type, while PTA using video modality is more accurate with spontaneous speech compared to read one regardless of the signal length.