Ability to server mosaiced imagery up as one complete image. Not have to worry about prepossessing, mosaicing and re-projecting data. It is fast and efficient, much better than serving the data out through a map service. You can also do analysis on the fly (NDVI for example)
What do you dislike?
Requires substantial overhead on your arcgis server. We fortunately scoped this out during the initial stages of our infrastructure build, so it was taken account. There is a steep learning curve, that is not overly well documented, however playing around, and asking on the forums will certainly get you where you need to be.
Recommendations to others considering the product
It requires a substantial overhead on your existing ArcGIS Server, however it is well worth the additional costs associated as it truly streamlines and improves your ability to serve out imagery
What business problems are you solving with the product? What benefits have you realized?
We have automated the creation of numerous image services. Data is placed into folders on a shared network drive. An automated process then kick in and creates the necessary files (including generating a cache)
* We monitor all ArcGIS Image Server reviews to prevent fraudulent reviews and keep review quality high. We do not post reviews by company employees or direct competitors. Validated reviews require the user to submit a screenshot of the product containing their user ID, in order to verify a user is an actual user of the product.