"A necessary compromise for when a window unit simply isn't an option."
The 6,000 BTU DOE rating is a more realistic government standard than older specs. In your home, this translates to just enough power to make a small bedroom (under 250 sq ft) comfortable, but it will not achieve the deep chill of an equivalent window unit.
This is for renters whose leases or building rules explicitly forbid window ACs. It also serves as a temporary, portable cooling solution for a small home office or guest room where permanent installation is not desired. The primary reason to buy this is a lack of other options.
Anyone who is permitted to install a window AC unit should do so; it will be more efficient, more effective, and likely cheaper. Those sensitive to noise should avoid all in-room compressor designs. If your room is over 250 sq ft or has high ceilings, this unit is undersized.