IMC: "Easy" to get, cost efficient and probably(?) learnes you 95% of what you will ever need in real life as a PPL. But you still can't go anywhere because it is UK only and I can't imaging myself going fo a leasure flight round the flagpole in IMC - I am like to need the IR when going cross country, and that is likely to be across the channel
The general idea in European touring on the IMCR (which I did for a few years) is that one departs the UK is less than great weather, climb to VMC on top before the airspace boundary, continues VMC to say La Rochelle and lands in VFR conditions. And the reverse going back. It tends to work quite well in the sense that it is a lot better than being legit VFR-only which is pretty limiting.
And the IMCR training, used together with 100% radio navigation (GPS/VOR/DME) enables one to cope with the, shall we say, occassional less than quite VFR conditions encountered enroute
I don't think I have ever done a long VFR trip on which such "conditions" were never encountered
But if you have no instrument capability, you can't do that else you kill yourself.
The full IR takes you into a different kind of flying. Sure enough you can still go drilling holes in clouds, and some do, but an IR gives you an implied whole-route IFR clearance which means controlled airspace falls away, so you climb to VMC, sit there the whole enroute bit, and then descend. The weather you are exposed to is different from that a PPL/IMCR is exposed to - it is high altitude weather, cloud tops, etc. You generally need a better machine than a Warrior, too, and many/most IR holders carry oxygen (I would never even depart on an IFR flight without sufficient oxygen). It's a great way to go places, but tough to do on the bottom end of the rental-wreckage scene. One still picks the weather; nobody wants to sit in muck for hours. On a nice day, one can fly IFR at FL100 for hundreds of miles, with a clearance all the way and nobody bothering you and dropping spanners in the works. In fact on any half decent day, if the European airspace owners operated their airspace according to ICAO (anything below Class A is fine for VFR) one would not need an IR half as much.
The FAA IR is nowadays not meaningful unless you are going to own your own plane, because it has to be N-reg.
A cut-down EASA IR is being promised but is at best 2-3 years away, and there have been so many false horizons on the IR front that I don't believe anything will happen.
The JAA IR syllabus is not intellectually hard. Most airline pilots are not intellectually that sharp. Anybody who could scrape an o-level pass in maths and science could easily pass all the exams. I know a bloke who can barely count and he has passed all 14 CPL/IR exams, on a very part-time basis (over years). It is just a huge memory exercise because so much of it is bullsh*t which doesn't relate to the real world. I have never done the JAA IR exams but have seen the material. There is a time/effort tradeoff in that you can spread them out if you are not too bothered about when you get there, but there is an overall time limit and if you don't complete the IR flight training itself in time (and that does cost serious money - it's currently 50hrs dual training, with no credit for anything previous short of another ICAO IR) then you have to either do it all again, or find a country which lets you do the flying while accepting your expired exam passes.
As I say, the way one has to play the "IR" game is backwards: can you afford a decent plane. If not, forget the IR. If so, then you can start throwing some options about... but I would not wait for an easier European IR.