If you closely watched the growth and transition of SharePoint, the majority of SharePoint implementations in the early days were unsuccessful for various reasons to name few "lack of product knowledge", "solutions delivered were complicated (reinventing the wheel)", "not user friendly due to lack of awareness & training", "over budget", "resource consuming", "high support and maintenance cost" and so on. Most of these could have been avoided or simplified with in depth technical/product knowledge augmented by well-planned Governance, training and support & acceptance from business user community.
Adoption is a key factor to successful SharePoint implementation. Getting business users to adopt the technology and become champions of the business process is the key driver to a successful SharePoint implementation at any organization. Business Stakeholders should understand that they have to help to drive SharePoint adoption.
SharePoint is designed to empower the Knowledge Worker. The only way to truly engage the Knowledge Worker is to allow them to have input into the functionality of SharePoint which makes them more productive.
Needless to say "Planning" is the most important every phase of the SharePoint implementation projects. If you take the time to plan SharePoint environment properly and include all the right resources, then the implementation should go much smoother.
SharePoint farm architecture which includes the number of servers, how big should be the farm, Capacity planning, Scalable Information Architecture and Classification, load balancing, database clustering and caching to improve performance. If the farms are geographically distributed, then synchronizing the centralized data across geographic regions, redundancy and failover strategies, data backup & restore is the most challenging part, unless everyone is connecting to a single data center directly, which implies use of Internet lines instead of MPLS connectivity over WAN, leading to other pro and cons.
Governance plan defines the service, roles, team, technology and the policies. Governance planning is even more important in SharePoint 2010 because the increased emphasis and availability of social computing features means there are more types of content to govern. Key areas are people, process, technology, and policies to define a service, resolve ambiguity, and mitigate conflict within an organization, web content management, records management capabilities, sharing metadata across multiple site collections, Document Retention, release management and disaster recovery process etc
If the user base is extremely large, then Introducing socialize governance within a large organization where process is something new and hard to put in place. Also requires a micro level study by the SharePoint Enterprise Architect to evaluate the data limits, rights limit, and departmental use of data. Growth patterns of data over a period of time for different departments would be different and to keep track of such policies on a regular basis to mitigate Data volume growth risks poses a bigger challenge.
If portal has too many customized web parts, then performance becomes a bigger challenge. To lay down architectural rules for design and coding of such components so that it meets the performance criteria.
Big challenge is to educate the business users to use the SharePoint in the "right way". In essence "Effective Planning and Governance", "Change Management", "User training" and "Continuous Support" is the key to successful implementation of SharePoint organization wide.
