What do you like best?
Ant can basically build anything - or wrap the build of anything, really. It is highly customizable and configurable, and can be used for most any kind of software build process or automation, even mixing and matching different builds (c/c++, java, etc) and driving them from the same build tool.
What do you dislike?
Convention beats configuration, and there are a whole lot of other build tools out there that have established conventions, pluggable features, etc. With ant you have to "roll your own" system for most things, even for very lower level things. If you need to highly customize (i.e. do it differently from most everyone else doing the same or similar) and control every detail of your build, then ant will let you do it. But this isn't a best practice - the more you can follow convention for java builds (maven) or mixed builds (python wheels from makefiles, ruby tars from rake, etc) the more you will be able to get contemporary help and solutions.
Recommendations to others considering the product
Look to use a more convention-based tool if you can, if you think you need this level of absolute and total customization it is likely you're doing something else wrong with your design/architecture.
What business problems are you solving with the product? What benefits have you realized?
I've used ant to build various software systems, and it did a fine job. The benefits were that it could build anything we wanted, and produce exactly the build artifacts we needed. Problems were that once the person who wrote the antfile had moved on, even to another group/department, deciphering what they had done (and why) often involved a fair amount of heads cratching and experimentation.