I really like this hotel a lot. Have stayed a few times for one night each before early flights out of the international terminal, and in addition to being as conveniently located as you could ask for, it's also a remarkably nice hotel. Rooms are spacious and modern, ramp views are great if you get a room facing the airport (and extremely well soundproofed), and the staff are generally friendly and helpful.
But perhaps my favorite part is the club lounge, which has a remarkably excellent evening food spread with a good amount of variety from night to night and easily enough food to make a substantial dinner out of if you so chose (and even a decent number of healthy options). There's even a make-your-own-trail-mix station with to-go bags.
The club breakfast is good enough but more ordinary, but I really thought the evening spread was notably well above the North American below-luxury-hotel club lounge standard. Alcoholic drinks are chargeable but that's par for the course in this part of the world.
Whether it's worth the often substantial price premium over the other airport hotels is up for debate, but it's worth noting that the price does at least combine both a great hotel and the best possible location if you're coming from or heading to a flight, though the Delta, which I haven't tried, is a close second on that measure. The other airport hotels all require a shuttle to and from the terminal which is a big downside if you're using the hotel for airport access, but if you just need to stay in northeast Calgary and especially if you're going to have a car, the others may be easier.
(The new Westin is also nice enough, but IMO the Marriott is nicer mainly for the bigger rooms and a better Club lounge food spread; the Westin arguably has a better gym and perhaps better non-Club food options.)