This dissertation addresses a gap in the field of designing adaptivity for ubiquitous systems by taking a critical look at the notion of "adaptivity" from the perspective of user experience. Through a set of detailed case studies of several different systems, I develop a set of concepts related to the experience of adaptivity. These concepts are supplemented by a set of design considerations that can assist in designers in thinking about key issues connected to the concepts. My work is a first take on untangling the complex relationship between ubiquity, adaptivity and the design of novel systems. Through a collective case study, I examine the differences between the intended and actual experience of three adaptive systems: the Reading Glove, Kurio, and socio-echo. The Reading Glove was an interactive storytelling system involving a piece of wearable technology that allowed participants to trigger story information by picking up objects. An adaptive component guided the reader through the story by recommending objects to interact with next. Kurio was a museum guide system that involved playing an educational game distributed across a set of handheld and tabletop devices. The adaptive component attempted to gauge the appropriate learning level in assigning tasks to each individual. Socio-echo was a group game played in an ambient environment, where teams of players had to coordinate their physical movements to solve riddle-based levels. Characteristics of the group's movement, location and position were used to adapt the system's ambient feedback system. From the analysis of these cases, I draw out a set of interrelated concepts that are useful for designing adaptive systems. The experience of adaptivity is impacted by the user's awareness of adaptivity and the interpretation of the adaptive effects. Factors like trust, surprise, augmentation, legibility, collapse, confusion, control and choice also play a role in grappling with intelligent components within complex systems. This research highlights the complexity involved in designing the adaptive components of computing systems making use of tangible and other novel interface styles by examining some of the experiential effects of these new interaction paradigms and how they relate to the intentions of the designers.