We were lent one of these and found it has some very good points but you do also need to be careful of a few things.
The cot is very light and folds up tiny so is great if you have to carry it around. It is reasonably easy to put up once you have figured it out, and our baby seemed perfectly happy sleeping in it.
However it does have some potentially big minus points to watch out for!
Firstly, the mattress is more like a pad than a normal mattress - as it's designed to squash up small, it is not rigid and not very thick. This means that it might not be very comfy when used on a hard floor - we put something soft underneath or used it only on carpeted floors. It also means that most fitted sheets will not fit - apart from the size and shape being unusual, anything with elastic will scrunch up the mattress as it isn't firm. My mum eventually made us some sheets where you put the mattress inside and button them, like a duvet cover - before that we had to use flat sheets but they tended to come untucked.
We also found that even a quite small baby could move the cot around by lifting his legs and kicking against the sides; and I have heard stories of older babies (5 or 6 months) being able to tip them over once they can roll. So please don't EVER use one of these on a raised surface or near any hazards, even if it seems safe! And I would not recommend it for older, strong and active babies.
Finally, getting the cot back into its bag is a bit tricky as it tries to spring back into shape, so it can be a bit of a hassle, though this is only a minor disadvantage compared to the size and weight advantage it has over other models.
In all, I would recommend this provided your baby is still small and not too active, and if it is used on a soft surface and where rolling or movement would not be a problem. But for older and active babies, a more stable style would be safer.