MartyHulskemper nails the description, so I am listing some specific examples.
1. Installing applications stalls other action/task
Presumably, installing application actively access your flash drive and this basically freezes your system temporary even it is non-intensive application such as simply non-flash based site browsing.
2. Downloading large file stalls other action/task
Just as #1, but again this is writing/accessing your flash drive.
3. Copy/Write from PC to Tablet by USB
Small files flies. Big files inconsistently but relatively frequently stops/freezes. Presumably some sort of issue from writing to flash disk.
4. Slower PDF opening (I am speculating this)
Compared to my former system, which was dual core, opening large PDF is much slower and almost consistently gives me "No response" Error. This I am blaming on the reading from flash drive is somehow the issue.
So You will encounter the problems here and there as I/O is pretty much used everywhere.
Previously Owned Devices: Xoom, Samsung Galaxy 10.1, Samsung Galaxy 10.1 4G LTE VZW, Galaxy Note 10.1 32 GB, Transformer Infinity 32 GB
Currently Owning Devices: Samsung Ativ Smart PC 64GB, Ipad 2