Bought a Beko heat-pump (DPU-7360 GX) in March '14 - as we were moving to somewhere with no outdoor possibilities and pre-cast concrete walls (and I didn't want to cut a external vent hole).

Seven years on, we love it and wouldn't go back to a hot-air unit.

Super economical and notably less shrinkage.

Yes a cycle takes longer - but living with that has been easy for us.

Lint filter maintenance is easy - but more important, as the air goes round & round.
No lint ever gets out with the exhaust air (as there isn't any).
It all ends up in the filters. 

If you don't keep them fairly de-linted, the cycle time extends as the efficiency drops.

There's usually a warning light for this.