There are 2 things that I dislike:
1. There are a few bugs in the internal programming logic of the CPM framework. Although the Pega support team provides hot fixes, on several occasions these hot fixes have introduced issues of their own.
2. Creating a user friendly UI is difficult in the Pega product itself.
Select Pega if
1. UI requirements are not too complex. OR
2. A strong foundation that is scaleable and extensible and is capable of supporting several applications is needed.