Stayed with one friend @ Carlo's apt in Sept 2013.
- on Frederic rental: very good, very responsive, very helpful, very everything ... in a nutshell its very easy to book with him, and he has good advices for Amsterdam. Did not try the bike rental though, only 1 flat.
- the flat is located in Herenmarkt6, 1st floor. The flat is small but very clean. It is ok for a couple, but if you are 2 people sleeping in 2 different beds, one will have the real bed, the other one the couch. And the toilets + shower are located in the bedroom. So you need some organization... Separate bathroom could have been better. But perfect for a couple.
To reach the flat you need to climb a few stairs, and the "slope" is like 60degrees ... you have been warned!
Great location, 10 mins walk from central station, nice area, but can be very noisy (and I mean very) at night, like drunk guys shouting at 3am ... this is amsterdam, but if you want a super quiet place you may want another location.
Price/Quality was very nice in the end.