Your program's limitations:
- What platform/OS it should run on.
- What range of inputs are valid.
- How large an input, memory-wise, it can accept (such as an input file).
- How much memory does it consume.
- Where is its performace bottleneck (file I/O, number crunching).
- What has not been tested (coverage holes).
- The limitations of other modules/libraries it depends on.
How it compares against other well-known programs which perform similar functions (CPAN modules, other freeware, commercial software).
- Advantages: Is it free?
- Disadvantages: Is it slow? Does it have a lousy user interface?
Where it was last night (that's a joke :)