Quoting from CA official announcement:

CA today announced the results of an independent global study that highlights the mixed results companies are experiencing with server virtualization—as well as critical success factors discovered by early adopters.

According to the study—which surveyed 800 organizations around the world—44 percent of respondents who said they had deployed server virtualization technology were unable to declare their deployment a success. Inability to quantify ROI was a key factor in their reticence to definitively claim positive results.

...

For organizations claiming success with virtualization, the most important factor was being able to measure performance of the virtualized environment. Other key success factors cited in the study include diligent inventorying of server assets and load distribution, and thorough investigation of available technology solutions.

...

The survey was conducted in January by The Strategic Counsel, an independent research firm. Of the respondents, 30 percent were from North America, 37 percent were from Europe, and 31 percent from the Asia-Pacific and Japan region. Of the organizations surveyed, 67 percent had between 10 and 99 physical servers, and 22 percent had more than 200...

No suprise here: in part virtualization market is still immature (despite IDC claims for Virtualization 2.0), in part technology seems so easy to implement that customers usually believe they can approach a complex enterprise project after a successful experience with VMware Workstation (or corrispondent).

Underestimation of virtualization challenges, something even system integrators are guilty of, leads to not properly invest in staff training and/or in professional consulting much before the project is set to start.