It's alright from what I've seen. The idents are pleasant and relevant enough but there's an overriding cheapness/half-arsedness about it, appropriate I guess. If they were going for the 8-bit retro look they should have gone the whole hog and not bottled out by using, ugh, Arial Rounded.
New logo looks odd; the two Ls don't sit right.
The previous look was probably the most ambitious and well-rounded Challenge had, spoilt by VM giving up on the channel and then bolloxed up entirely by Sky. This is an improvement only because of how the last package was allowed to degrade but doesn't come close in terms of concept and execution.
Obviously with C4 and ITV they're unwilling to dilute 'their' active brands (hence why Golden Balls only showed up in its dying days on ITV1).
Family Fortunes and Millionaire surely both count as active brands?
Millionaire was hardly in it's heyday when first picked up by Challlenge, and the Family Fortunes we see is very different to 'All Star' eps shown on ITV1 with Vernon.
It is not too bad, although I have not seen the new breakbumpers or idents yet. I believe my version is better though, as it incorporates more 8-Bit elements.