Shark
The Shark BU3521 is an ultra‑lightweight cordless stick vacuum with a 1.3 L auto‑empty base that empties debris and recharges the unit automatically. It offers up to 40 minutes of runtime, HEPA filtration and a versatile brushroll that adapts to carpet and hard floors, targeting pet owners and allergy sufferers in small‑to‑medium homes.
Pros
Current
$249.00
Average
$298.64
Lowest
$168.95
Highest
$399.99
Lower = better sales rank
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Cons
Expert Opinion
Professional reviewers and editors are not directly quoted in the available sources, but product‑page language emphasizes engineering claims such as powerful debris pickup, deep‑clean capability across surfaces, and convenience for pet owners. The auto‑empty feature is highlighted as a differentiator that keeps the vacuum "always ready," while the lightweight design and HEPA filtration are presented as key benefits for allergy‑prone households.
What Users Say
Everyday users are not directly quoted, but the inferred sentiment suggests appreciation for the hands‑free auto‑empty convenience and the light stick weight that eases maneuverability. Common concerns likely revolve around the heavier combined system weight, the limited 40‑minute runtime in higher‑power modes, and the need for a permanent outlet for the charging dock.
Common Complaints
Heavy full‑system weight when dock is included, runtime reduction in high‑power modes, absence of a brushroll shut‑off, need for a permanent power source for the auto‑empty base, and a relatively long 5‑hour charging cycle.
How It Compares
vs. Shark Vertex Pro
Advantages
Disadvantages
Choose the BU3521 if you value auto‑empty convenience and a lighter stick; opt for the Vertex Pro if you prefer a traditional stick without a dock and can tolerate a heavier unit.
vs. Dyson V15 Detect
Advantages
Disadvantages
Select the BU3521 for auto‑empty convenience, HEPA filtration, and lighter handling; choose the Dyson V15 if maximum suction and sensor‑based cleaning are top priorities and you don’t mind manual emptying.
