A few professionals reviewed Lertap 5 shortly after it first appeared, and, more recently, two leading textbooks have made reference to it.
It's possible to read most of what the reviewers have said to date by looking at a summary of their comments (links to a Microsoft Word document).
One of the reviewers was Professor Nathan Carr. In a fairly recent book (Carr, 2011, p.209), Carr referred to Lertap 5 as his "... personal favorite for reliability and item analysis ...".
The Handbook on Measurement, Assessment, and Evaluation in Higher Education (Secolsky & Denison, 2012, Table 20.3) referred to Lertap5 as "... a sophisticated commercial item analysis program that works with Microsoft Excel .... is capable of calculating standard item analysis values as well as differential item functioning (DIF), distractor analysis, and response similarity analysis .... (it) is very flexible and robust and capable of handling up to 10,000 items and over one million students."
An excellent text and technical reference book by Haladyna & Rodriguez (2013, p. 387), stated that Lertap 5 is "... a very versatile item analysis program with many options, including DIF ... ".
Other references to Lertap may, of course, be found on the internet by using a search engine (such as Google).