I used this on a long weekend to Italy (4 nights).
Vacuums pretty well and the seal keeps. There is definitely a lot of technique needed to ensure it compresses properly as I required some trial and error. Anything that can bulge from the vacuum will prominently, so practice with it a bit first before you travel to get the best results. BUT I will certainly keep using it and seeing how far I can push it on longer trips.
Packing a book proved to be the hard part. Mine was a moderately thick pap...