Established in the past year, they're an excursion booking agency working on commission. (like Viator or City Discovery), not a tour operator. So they have no real control over the quality of the excursion.
Like Viator, they take some of the hard work out of hunting for an excursion & they're way cheaper than ship's tours (though that's not difficult
). With a bit of ferretting you could book direct with the operator a bit cheaper, but - esp if it involves front-money - you'll find it easier to get redress from them than from some e-mail address in a far-off country. Haven't used them, used Viator withot problem a couple of times in specific circumstances. And heard very little about them, nothing negative, but its early days yet. They claim to offer excursions world-wide, but currently they're majoring only on Europe.
If you're tempted, double-check their ABTA credentials.
And come back to let us know how you got on