HiFi+ has a review of the Isis by Roy Gregory that is fairly accurate. The Isis are detailed, coherent, holographic, and provide heft at the lower end to give music some body and presence.
They need special attention to component matching, and some may find them overly detailed or dry. Finding a good amplifier was actually a bit of a challenge. I'd want at least 300 watts, and if considering tubes, think of something with a large transformer.