I've used them several times now. It is essentially a travel agency that is branded United Cruises. This company operates as "Luxury Only" which is part of "World Travel Holdings". Any available fare should be bookable with them. A few things to note:
- If you have a United Credit Card, you will earn a higher multiplier on your cruise fare.
- For expensive cruises, the miles you earn will be capped at either 45,000 or 60,000 (usually) per cabin (not per person). So, if you book a cruise that costs $10,000 and it is a suite, you'd probably hit the cap before getting the full multiplier of miles back.
- Some cruises/cruise lines offer additional bonus miles. For example, a Seabourn sailing may give you an additional 25,000 miles per stateroom (not per person).
- Many times throughout the year, they'll bump the earnings up to 10x miles per dollar (from the normal up to 7x per dollar).
- The miles you earn is on the commissionable fare, not the gross fare. This means if your cruise is $1000 per person all in, the commissionable fare will probably be somewhere between $400-800 after you take out port taxes and other misc fees (which aren't well disclosed, but are subtracted by the cruise line, not United Cruises).
- They charge $25 per person booking fee. No way to get this removed.
- They've always been able to match any other published price at the time of booking, but you may have to push them to figure out the promotion another TA or website is offering. Sometimes there's a code associated with the offer such as "XY3" or the like.
- If you have status with the cruise line or any other perks you normally get, they should apply here as well.
- You don't earn any Premier Qualification Dollars (or anything towards Premier Status) by booking with them.
Bottom line, if you go in prepared, this can be a pretty good deal (if the cruise is expensive enough to offset the extra $25 booking fee you have to pay them). For me, since I normally book expensive cruises, I'll end up earning many tens of thousands of miles (or more) per cabin by booking with them.
Hope this helps!