Firstly I need to admit to being a pramaholic! This being my 5th purchase in 2 years, but it will be my last!, I just wish I had found the mutsy when had my first child.
I bought a mutsy as i was having my 2nd child and needed a double pram/buggy as child no 1 is only just 2 and wasn't walking far. The mutsy was the only system where i could alternate between a double and single seat and isn't the size of a small minibus!
I have the urban rider chassis, a single seat, the duoseat and a maxicosi baby car seat which is also compatible. When just taking the baby out its dead easy to put the carseat on the chassi without waking her up. When I have both children the duoseat is fab and can easily fit through doors etc. Although easy to push anyway I bought some whizzy wheels which are great for doing tight turns in shops. The single seat can go on the chassi forwards or backwards so is great for keeping an eye on small babies but also good for nosey toddlers.
There are really only a couple of downsides. Although it all fits in my car easily (a 307) I have struggled if we have been in other smaller cars. Also the duoseat is heavy to lift in and out of boot, so if you are always in and out of car, this is probably not for you. Finally my son is tall for his age and is nearly touching the hood of the front seat of the duo, however the hoods are removable so I can easily take it off and then it is fine.
I plan on getting a mutsy step up board as my son is now walking more, then I can continue to use the mutsy with my youngest and the single seat as I really love it.
The mutsy isn't cheap but is sturdy, looks fab and really versitile. It is ideal for a first child if you intend having more children, as you can buy extras as you need them, however if you are someone who uses public transport or has a small car I think you would be better off with the traditional double buggy.