Yes of course. ISI journals are considered highest quality journals (Even though it's a bit debatable). All or most of the research institutions consider ISI indexed papers as the gold standard.
Impact factor (IF) represents the acceptability of the journal (or acceptability of the articles in that journal). Higher IF means better acceptability. For instance, IF of a particular journal in 2015 would be = A/B
A = the total number of citations of that particular journal in last year (2014)
B = the total number of published articles in last year (2014)
If a journal published 200 article in 2014 and the journal was cited 400 times in 2014, the IF would be 400/200 = 2.0