We have a combined washer/dryer and it is a condenser one too. It is a black art getting things to dry (because of the odd way condenser ones work adding water to take it away and all that) but my wife has worked it out and it is fine.
It is a Zanussi and we have had it 8 years, only needing a £50 replacement set of bearings in that time.
But we do avoid using the dryer as much as we (ie me) possibly can.
And we have twin girls (aged one) so it has been hammered for the last year.
But I do agree with the above, condenser ones aren't as good (but easier to fit as you just need a standard waste pipe) and if we had the room I would certainly go for separates – even if only because the larger drum on a dedicated dryer is much bigger so things dry much more quickly.