I like that inteliuss has such great information, it's not just names but also addresses etc which makes searching for someone much easier than other sites out there with only first or lastnames! They have no phone numbers so you can't call them up directly if they don't live in your area either (like google maps does).
It would be nice though because sometimes i need more info then what my local records give me from an address alone - especially when looking at family members who may reside elsewhere-but this site gives all kindsa useful stuff as well :) nothing really bad except maybe being able to search by email instead of having to put fullname/lastname into each field since some emails are very common :( still use regularly tho :D.