1) The best feature in my opinion is the quick implementation of any ideas/wireframes that have already been designed on the platform.
2) It is very easy for non-data/technical users to learn after a few introductory sessions
3) The ability to cross certain things between Target and other products in the Adobe Suites
1) To take advantage of the full capabilities you have to implement it with SiteCatalyst - implementing the two is not an easy process, even though they are both made by the same company.
2) Data discrepancies between Target and SiteCatalyst - they contribute to metrics differently and numbers may be off between the two
3) Slow load times that can affect data pulling
4) User interface will occasionally reset after you have selected multiple options from the drop down menus
If you are considering buying Adobe Target then I would research what it actually is and ensure that it will do everything you need it to do. If it won't then I would recommend looking into other Adobe products to see if they will fulfill your requirements. It is important to ensure that you know which products you will need before you buy one and not the other.
After buying it I would recommend you immediately watch training videos on it to ensure you are using everything it has to offer.
Using it for web analytics where it has the benefit of quick implementation of ideas already placed on the platform. Allows marketers to take control of a portion of their development work and not rely on another team.