If you have a decent IFR-capable and airways equipped plane, have the ample time to do the JAA PPL/IR, and want to go places seriously, then get the IR. It transforms European touring capability, reducing the random-planned trip cancellation rate from about 75% for pure VFR to about 25%, and this is reduced further if you have de-ice, radar, a decent operating ceiling (say 25,000ft), etc.