I got one for my son when he was 4 months old (we hired it) and used it until he was 7 months when he was ready to go into the cot and was trying to roll onto his tummy
It was the best thing we could have done to settle him and he slept so much better when he was in it. We also co-slept but less after obtaining the hammock because he was happy to sleep there instead.
The Amby is VERY portable too!!! It can be moved from room to room and it is easy to put together. Far easier than putting up the portacots which is great if you go anywhere.