I agree with @James Carlson that AirBnB is the disruptor or trendsetter at this time. I've been on the platform as a guest and a host. Yes, I am a millennial, and I think that their UI is easy to work with, not clunky, and at the top when compared to others within the vacation rental, home sharing, and sharing economy platforms.
From my personal experience, their quality of customer service is pretty good, and it seems that the company gives their representatives adequate power to go beyond each user's expectations when the opportunity arises, whether that involves providing extra credit to use during cancellations, replacing items that were damaged or taken during a stay, etc. I think that they have an emergency system/teams in place to help with immediate resolutions, similar to how concierge services work. As a host, I've been personally called by AirBnB to host guests who had their original reservations cancelled in the surrounding area, so that's been reassuring to know that they would go those lengths to help guests out of unfortunate situations, particularly important if it's in a foreign country (I've never had this happen to me personally when I was abroad though as I was lucky with great hosts). However, I've heard that one of their growing pains is the longer and longer wait times on their phone lines. I rarely encounter any situation where I need to speak with them on the phone (their response rate by email is OK), but I do hope that when I need to speak with someone, I don't have to wait more than 5 minutes to do so.
The appeal of AirBnB, as opposed to the standardized consistent hotel experience, is the opportunity to find the type of vacation or stay that each person wants, whether that is living with/like locals in neighborhoods where hotels don't exist or can't offer, getting more space with the facilities you want (i.e. kitchen, backyard, personal jacuzzi, theatre room, etc.) perhaps at a more affordable price, or sharing a home with others where you can share a home-cooked meal or exchange stories around a fire pit at night. From a consumer point of view, it comes down to having a wide range of CHOICES. Sometimes, I do want to stay in a hotel and other times, I want another experience that may be available on AirBnB. On the flip side, as a host, I have complete control over what I offer and I feel that the fees that AirBnB charges are worth the platform and service that they provide. That can always change as the industry adapts. And perhaps, there will be another competitor that comes along and if they have a smoother platform, faster/better customer service, better support tools for both guests and hosts, lower fees, and equal or more choices, then they can overtake AirBnB.