What I probably like the most about Trulia is their mobile app. It has a nice minimalistic look and a clear map and list feature. They also have custom filters you can set to narrow your search. I have used Trulia for both personal and business use because Trulia has listings the MLS does not, like by owner listings.
Trulia does have filters on their site that can be used to narrow searches, however, it does not always filter out all of the unwanted properties. For example, if you were to mark "laundry in unit" as a filter, it for some reason will still show listings that may not have laundry in unit. Similar with the pet filter, it may show properties that do not specify a pet policy, which should be a required question when someone posts a listing. Another issue with the way their search is constructed is that if you are looking for a listing that is 2 bedrooms and you set the max price at $1,000, Trulia may show you an apartment complex with a price range of $1,000-$3,000. What that can mean is that a studio apartment at that building is $1,000 but a 2 bedroom is really $2,500, which would not fit in your search criteria.
It is easy to use and convienient, however, I would consider using this along with other applications because no listing applications has every available listing.
A benefit of Trulia is the convienience. Because they have a relatively well designed application, it is easy to use on the go or to find listings near by. They also have a very simple and clear process for listing properties.