1. Difficult to change the heads due to the stiff and imperfectly aligned joints
2. Very short battery life in max power. Maybe not a con due to the fact that the battery technology sucks.
3. Dust bin can be a nightmare. Comparing to Dyson's pull-down design, you need to detach the bin and pull the dust into trash can, like pouring a cup of tea. The dust goes everywhere. I just couldn't find a way to solve the issue.
4. Small dust bin. You probably need to clean up the dust bin frequently if one or two animals at home...including small kids i meant.
5. HEAVY! Didn't have the number, but it definitely feels heavier than Dyson V8, V10.