I have (and use) both the Quinny Zapp and McLaren buggies.
The Zapp is very easy to manoever, particularly with one hand and through busy streets. Its lightweight 3 wheeled design is not conventional. It can be a little tricky to fold down (compared to a McLaren) and particularly due to this I would not recommend taking it on the tube if you plan to fold it down. You can put it in a bag but compared to the McLaren this is just nowhere near as convenient (McLaren can be single handed fold down with a shoulder strap).
We bought a bag that attaches to the back (from ebay) and this allows it to offer some storage (lightweight) which seems on par with the McLaren.
We never had a problem with our daughter sleeping in it (she takes after her dad and can sleep anywhere), we used it on holiday when she was 5 months old. However, as it doesnt recline some babies may not take to it.
One big advantage is that you can remove the buggy seat section and clip in a car seat. So if you are going on holiday with a young baby it could be perfect.
We now have the 2 buggies mentioned plus a Mamas and Papas Pliko P3. The latter does everything but is heavier, less easy to manoever and will easily fill your car boot so is left assembled in the garage for local shopping. The Zapp will fit in the smallest car (I even think a mini boot) as it folds v.small. The McLaren is the halfway house in terms of more conventional design/looks but does the job well.