At first I thought it was more of a way to keep track of a normal person's belongings, but with the appraisal feature, it seems to be more for collectibles.
I was specially intrigued by the idea of value variation and notification. "My refrigerator's or bed's market value will never increase", thought I while shaking my head at the website.
With collectibles, art, and a few more valuable items like cars and watches and, this may actually make sense. And I can rest knowing this service is definitely not for me.
It's an interesting idea and it very well may succeed, but I think even here on HN its affluent target demographic will be at most a small percentage of readers.
For the owners, this is a great way to find out what stuff people have so advertising can be targeted: "Oh look, Billie has two x's, so companies selling a similar x should really advertise to him/her...and pay us for the privilege"
What I really like about this is that I doubt many of us give a crap about cataloguing our possessions....until there's a freakin' app for it.
Though, I'm not sure how I feel about some of their caveats, most notably 1 and 2 below, which correspond to exceptions about disclosing your data to third parties  and deleting your data :
 Unless legally required to comply under court order.
 Unless compelled by a legal, court, judicial or administrative order to retain it.
The problem I see is that it's going to be hard to get people to enter all of their things into an app on an ongoing basis. It makes life seem more complicated by adding an additional step. If users fall behind and fail to enter items the app loses its usefulness. It seems to me the best thing Trov can do is make adding new items as easy as possible.
Then it'd be nice for vouyerism and conspicuous consumption, maybe it'd go 'viral' when view source made it to twitter. Otherwise you better pay people for filling out an advertising survey.