Technical advancements in virtualization and Service-oriented Architectures, the technology backbone of Cloud Computing (CC), along with the availability of high speed Internet has escalated the performance of CC in terms of elasticity, throughput, agility, or response time. However, according to the Gartner's Hype cycle of 2014, CC is at the 'Trough of Disillusionment', which hints at 'waning of interest as the implementations fail to deliver' . The reason for this situation is the lack of a methodological impact analysis for adopting cloud-based services in an organization. In the context of CC an impact analysis is complicated due to the complex architecture of services and presence of influencing factors from multiple dimensions (technical, economical, and organizational). This paper, therefore, extends and evaluates the methodology 'Impact Analysis Methodology for Cloud-based Services (IAMCIS)' that quantifies the impact of cloud-based services before they are adopted in an organization . The methodology is illustrated in combination with a use-case obtained from a survey conducted with 17 organizations (with varied domain of expertise, size, and geographical scope), who plan to adopt or have adopted cloud-based services for fulfilling their IT requirements.