This apartment is amazing!! It fit our needs perfectly, in fact it was even better than we could have hoped. We were two couples travelling with our 3 children (2 seven yo's and a 3 yo) and the layout of the flat is great. We could put the kids to bed at night and have a drink and a chat in a beautiful loft style apartment.
Then there is the location, about which we struggle think of a bad thing!! Metro 100yds away, river 5 min walk and all of the lovely cafes, restaurants, shops that you could ever want, right on your doorstep. But it gets better - the side street location means that it pretty quiet too!! Be prepared that St Germain is a great, lively, cosmopolitan part of Paris. Don't expect a sleepy quiet area but also don't expect thumping clubs until 5am either.

We really are struggling to think of any constructive criticism! We could, perhaps, suggest some form of TV etc. but this is only because we had small children to wind down after a busy day. Really, really not essential, however!!! The Wifi was excellent so they could use ipads etc.
The linen provided was spotless and so was the general cleanliness of the whole apartment. Just note, as others did, that it is the 3rd floor and it quite a narrow staircase.
We will recommend to friends we think it could suit and would definitely consider using again when we return to Paris.