I purchased FTTF on our Liberty cruise a two weeks ago. It was well worth it. We were at the port early (10:30) and there was nobody in line at all and we were able to walk right up so it didn't help us there but by the time boarding started the terminal was jam-packed full. They called the VIPs and then before they were even out of the Captain's Lounge, they called Priority Boarding (FTTF) so we basically boarded at the same time as the Plats/Dias. We were able to go directly to our cabin, drop our carry-ons off and up for lunch. When we returned after lunch our luggage was waiting.
I had to visit Guest Services twice and both times the line up was very long but I was able to step right up - took me less than 2 minutes both times to do what I had to do - whereas I would think the people standing in those long lines would've waited for at least 30 minutes. I went to ask them to open our balcony dividers and the other time was to get stamps from the countries we were visiting - I definitely would not have gotten the stamps if I had to wait in that line.
We always purchase liquor from BonVoyage. It has actually been available for years but was not advertised, you had to call to order anything other than wine. They just added the liquor and mixers to the website a few months ago. The prices are comparable to what we pay in Canada so that price doesn't bother us. It was nice to be able to mix a drink in the cabin and sit on the balcony.