I had one.
Pre motor filter was supposed to be a thicker, anti-bacterial version of the standard filter. I noticed that suction DID drop off after a month of use.
Exhaust filter was a pleated HEPA. It was supposed to last a year. Nothing of the kind! After a few months the pleats split, allowing carbon dust to escape from the filter.
Suction power was pretty woeful at only 90 Air Watts.
Plastic used in the soleplate was rather flimsy.
Airflow through the machine from the floor nozzle was disappointing. There was an inspection duct that had a rubber flap that was kept closed in operation, by the suction of the machine. However, as soon as the motor was turned off, the rubber flap relaxed (read "opened") and grit/sand spilled onto the carpet. Very poorly designed ducting. I permanently taped the bloody thing closed.
Really, the DC04 was a major improvement. Altogether a better machine.