Battery powered glory or hype

Would like to hear details from those Audiogoners who have ventured into and out of battery powered equipment. Would like to know what battery powered sources add, substract. Also battery powered amplification. Its plus and minus. What to expect.

PS: I am eagerly awaiting the arrival of my Final Music 5 and 6. Both preferably DC battery powered and optionally powered to mains with a tube regulated power supply. 10 watts and a whole load of D batteries.

PAUL