How good is the 1-year IIM Lucknow executive program?

Frankly, everything falls on how you perceive the "good" you're talking about and what are your expectations from the degree. 

Course Curriculum:

If you want to know about the curriculum aspect there, it is pretty much similar to the 2-year program. In such courses, you also must realize that the syllabus covers all the subjects, but in a rush. Plus, if you're someone who prefers learning in-depth, be prepared to be disappointed as they will be taught on a surface-level only. 

Faculty:

The one-year-long executive program has the same faculties as the two-year-long program. The pedagogy of the course is also the same.

Also, another thing that you should note is that the campus is in Noida and not in Lucknow.