In theory, and anti-matter reactor be an excellent source of energy. It would be the perfect energy solution - the complete transfer of matter to energy. The only problem is controlling the vollitle reaction, and storing anti-matter.
The storing of anti-matter is almost impossible for the same reason the reactor is so powerful - as soon as the anti-matter comes in contact with ANY matter, be it air, water, metal, etc., the resultant explosion would be disastrous. Scientists are currently working on a way to succesfully store and and trasnport anti-matter, and as soon as that is complete, the reactor needs to be built.
So - an anti-matter reactor works in theory. We just need the technology to build and CONTROL one.
Storing the anti-matter is a difficult task indeed. A solution would be to synthesize the anti-matter from normal matter directly inside the reactor, thereby negating storage difficulties. Accidental and catastrophic destruction release would be very unlikely if only a small amount exists at any time. Synthesizing anti-matter (see Star Trek warp core) form normal matter is probably more difficult than containing the antimatter.