I'd like to propose the following 24 questions for a "lessons learned" session at the end of your project (or better at the end of each phase of your project). Over time, I have gathered a number of questions from various sources that I find appropriate to consider with the team at the end of a project. They are grouped in seven categories from governance to project support tools via management of risk, change, time, cost and quality.
Governance and Communication
1. What did the project committee do well that could be reused on future projects?
2. Where could it have done a better job?
3. How well were the organizations and users informed about the project?
4. Were appropriate communication channels and media used?
5. Did various audiences receive appropriate, timely information about the project?
6. Was too much or too little information communicated at any stage?
7. What changes were requested or introduced during the project?
8. Did the changes prove to be valuable, e.g., increased benefits, lower overall costs?
9. Were any project objectives compromised through the introduction of a change?
10. How many anticipated risks materialized, and how were they managed?
11. How many unanticipated risks materialized, and how were they managed?
12. What risks were well managed, and which could have been better handled?
13. Did we spend the appropriate time on risk management?
14. Was the project delivered on time? If not, please provide reasons with examples and any mitigation factors.
15. Was project governance established in good time?
16. Did the governance help make effective, timely decisions for the project's benefit?
17. Is everything in place to reap the benefits as soon as possible?
18. Has the project completed a review of its business case at the end of the implementation?
19. How do the actual project costs compare to the original estimates?
20. What cost more than budgeted, what cost less, and why?
21. How could costs be reduced on future, similar projects without compromising success?
22. Were the benefits reached in time with appropriate business ownership?
23. Has the project met its quality objectives?
Project Support tools
24. How well or badly were the support tools for the project assisting you and how well did they work?
I've been leading IT projects for more than 20 years at telecom and computer manufacturers: Thomson Sintra, Digital Equipment, NCR, Nortel Networks, Orange Business Services. My passion is Project Management and leadership and I run a blog on the PM best practices at http://dantotsupm.com/