Smartr Contacts has some of both, so let's start out with the hits. When it works, having a list of your most frequently used contacts appear when you first start the app is amazing. It just makes communicating on your Android device that much easier. Also, the ability to quickly see a list of your communication history with a contact can be a real time saver. Finally, since the Smartr Contacts app will load your calendar as well, you can also check your upcoming appointments from within the app.
There are, however, quite a few misses with the app as well. First, it did not accurately compile my text messages, so two of the people that I contact the most didn't appear anywhere near the top of my contact list because I only communicated with them by text message. Sure, I can always type in their name and select them, but I can do that in the stock contact app as well. Second, if you use a non-Gmail account for most of your correspondence, and don't have Microsoft Outlook on your computer, the Smartr Contacts app won't be very helpful. The app was great at consolidating my Gmail address book, which I use for work, but my personal email account was left out in the cold, making the app much less useful than it could have been.
Third, the menu system appears to not have been thought out very well. I thought, for quite some time, that if you wanted to change your account information you would have to essentially log out and then log back in. I wasn't until later that I discovered that you have to press the "Menu" button while searching for a contact, instead of on the home screen, to access this feature. Frustrating, to say the least. Also, there doesn't seem to be a way to consolidate multiple social networking accounts, and it doesn't include Google+ at all, again leaving out a large portion of the people I communicate with.