The shark NV501 was pitted against a Dyson DC14 Animal hair (Purple), older model before the ball. Vacuumed a room with Dyson, immediately followed by the shark and pulled a large wad of pet fur and ground in dust/dirt/sand. It looked like it pulled a lot, but the placement of the tall foam filter significantly reduces the capacity of the dust bin.
We bought the optional caddy, not worth the money, but is useful to convert it to a true and useful canister. The motor is too heavy to carry around for most applications and is not stable when the want is used to get into tighter spaces and further away from the base without the caddy. The same issue as with the Dyson - too many tools and not enough places to store them in the unit. Also some interesting tools, but not necessarily as multi-function as they would have us believe. The tools for other vacuums will not fit, because of the non-standard size hoses. The optional access tools are also well overpriced and if all are purchased, will more than double the price of the unit.
They claim the unit is quiet, but it is still a shrill high pitched whine. If used for a prolonged period, may give a headache. It is practically self propelled, when using the beater brushes, and cleans more on the return portion of the stroke as it lifts the carpet pile or knap. When brushes are turned off, it doesn't pick up gravel and sand off variable height tile floors, when turned on, it sprays the dirt forward, like many other vacuums. The tools and unit do not adjust to variable height flooring.
Easy to Use, Performs Well, Looks Great, Great Value, Easy to Empty Filter, Self-Propelled
Dust Chamber, Unbalanced