Tk Application:
Pros:
Truly stand-alone.
More professional (IMO).
Less system intensive.
Platform independant.
No worry about passing parameters.

Cons:
More in depth programming required.
No real cross-platform printing capabilities.
Less ability to be creative in appearance

Web Based Application:
Pros:
No need for perl to be installed on all client machines.
Avoidance of missing module issues on client machines.
Allows for greater creativity in appearance.
Accessible from anywhere.
Ability to use browser print feature

Cons:
Not stand-alone.
Requires web server configuration operation and maintenance.
Less secure due to greater accessibility.
Can be resource intensive (depending on user load).
Could run into permission issues.