AH - slings! Well, I am bit of a one-woman reviewer for them as we had All.The.Slings. I just couldn't decide for ages which ones I liked or didn't.
The scarf-type slings (like Moby wrap) are BRILLIANT when baby is really small but a bit faffy - as in: I could do it totally fine but dh always got it wrong and really stressed me out with it! They are also so soft to the touch, easy to wash and serve multiple purposes: emergency blanket, emergency pick-nick rug, burp cloth, breast-feeding 'modesty' scarf etc... and are breathable in the summer, unlike the polyester ones which gave us both really sweaty backs (and fronts, but that's pretty much inevitable if that's where you are carrying baby).
I personally didn't like the baby-bjorn at all : had really bad sciatica post pregnancy and the weight distribution is all wrong, all on the shoulders and pulled on my lower back. Also felt that dd's thighs were constricted and that her head wasn't well supported. But loads of people have it and love it!
Baba-sling: never worked it out, felt really unsafe. Again: we probably did it wrong.
And the winner was: the Erg-baby. Great newborn insert, great to carry on front or back and particularly brilliant when the littlies get heavier as the weight is very well distributed across the back and the hips. We actually still occasionally put dd in it as a rucksack for when we go on uneven terrains or somewhere where prams are impractical!
(Phew - anything to keep me from thinking. Give me more jobs to do!)