I used (tried) a BabyRock comfy carry or something I think it was called. anyway, Charlotte was about 2 months old, couldnt even stand it for 5 minutes. The mesh gave no support and she ended up looking like a rolled up millipede! lol It was crap and so uncomfortable for me, the length and positions of the ring and the padding and the mesh was waaay off.
For serious!? I saw a woman with a babyrock carrier the other day and her newie looked soooo cosy and content, I was thinking of getting one next time I fall preg!

DD and I both hated the baby bjorn. She was never comfortable in it because it didn't offer enough head support, I couldn't get anything done because of the positioning of it (it made DD stick out too far so I couldn't cook or wash dishes or anything), it was bulky and stiff and ugh. It wasn't expensive compared to some others and it offered fairly good back support and was easy to put on, in its defence. I only used it a few times though.