I've stayed at the Yotels at both LHR and LGW. The standard rooms are very small and best suited to just one person as to move around, the other person needs to be either standing in the bathroom or in bed, not to mention there would be little extra space for two or more suitcases, hand baggage and so on. Haven't tried the premium rooms so cannot comment, but I understand that they're double the size.

The beds are unusual - as stut says, the beds of adjacent rooms are located on top of each other -cabins either have steps up or down into them. I didn't experience any noise from adjacent beds so the sound-proofing is quite good.

+ Rainfall shower, one of the best I've ever had
+ Mood lighting helped me to relax
+ Good TV with a wide choice of music and TV available
+ In-airport convenience.
+ Convenient flexible pricing.
+/- 24/7 food and drinks available at prices less than a "regular" hotel - menu is fairly imaginative but not extensive
+/- If you're over 6ft 2, the beds in the standard cabins may not allow you to stretch out fully
- Standard cabin beds are not full doubles, closer to a single and a half, so it can be a "cosy" night for two.
- Can be pricey for a "full" night

I really liked them to be honest. I liked the modern feel and whilst minimalist, I didn't feel that it was no frills like a Travelodge. For a few hours and for when I can't face dealing with airport shuttles, nor wishing to pay through the roof for the on-airport properties, I'd go for Yotel again and again.

Would be interested to hear further opinion.

Mark