We have an ILS and NDB approach on one end and a single NDB approach to the other.
I suspect that as soon as GPS approaches are approved UK wide, we'll keep the NDB until it keels over and then it won't be replaced.
The NDB approaches are extensively used by every type of a/c, from C150s to B767s, but most operators prefer to take the ILS and a tailwind of up to 10kts if we aren't busy with departures.
From an airfield perspective, we don't technically need an NDB now, but to commit ourselves to not having one before GPS approaches are approved would require us to man 2 radar postions at all times, one for approach/LARS and the other for SRA's - that isn't going to happen in these economic times.
Word on the street is that once GPS approaches are approved in the UK and providing that each individual airfield to present a safety case, the minima will be reduced to below that of the previous NDB approach.