An increasing availability of miniaturized computing, storage and communication resources for personal wearable electronics devices as well as the availability of diverse sensors for human vital signs (e.g., heart rate, respiration) enable the development of a wide variety of wearable systems for ambulatory psychophysiological measurements. These systems pave the way for acquisition of quality data relevant for research studies or clinical practice in a healthcare domain carried out outside of the controlled laboratory environments. To date, there exists a number of such systems, however, neither the systems themselves nor details on their features are easily accessible by healthcare practitioners interested in their use for research or regular practice. This paper presents the results of our initial survey on the state-of-the-art in off-the-shelf wearable Body Area Network (BAN) systems for ambulatory psychophysiological measurements and their features. We first present a high-level overview and definition of such a BAN for healthcare use. We provide a detailed discussion on its relevant features and the issues influencing the system performance and usability, including: sensor specifications, system wearability, communication characteristics, battery lifetime, and so on. We expand this discussion towards a set of off-the-shelf BANs. Finally, we highlight some of the design challenges and open issues that still need to be addressed to make such systems effective for a wide range of applications, e.g., we review state-of-the-art for energy-efficient MAC protocols. This paper aims to provide knowledge to those interested in ambulatory measurements, on the set of available systems and their capabilities, and to highlight opportunities for practitioners or scientists in a healthcare domain, and to encourage them to reflect upon their system requirements.