You have to instrument your code as there is no progress bar or something that gives a running count of lines processed. And for what you are doing I would just use a checksum. All you want to know is: did it work okay? Not where some things differ in files, because you will just recopy to fix it.
And. Unless you got errors during copy, the probability of failure is really very low, except if you were ftp-ing from windows to Unix. You were not doing that.
#!/bin/bash
cd /path/to/oldfiles
export DEST=/path/to/newfiles
cnt=0
for fname in *
do
old=$(cksum $fname )
old=${old%% *}
new=$(cksum $DEST/${fname})
new=${new%% *}
cnt=$(( $cnt + 1 ))
[ $(( $cnt % 5 )) -eq 0 ] && echo "$cnt files processed"
[ "$old" = "$new" ] && continue
echo "failure on file $fname"
done