It is always worth asking these "is the IMC Rating worth doing" people what their budget is. If it is £1000/year then the "correct" answer is going to be NO; just keep renting the Cessna 150
In most cases, this turns out to be the case, and probably this is why most IMC Ratings are lapsed. But for pilots that do the right amount of flying in the right plane, etc, it is a great privilege.
I fly IMC (IFR) as necessary/possible but do find that most flights are in fact done in VMC (above, between or below the clouds; the first two not being legal for a basic PPL). But even if one is fussy about conditions, what the IMC option gives you is flying when the weather is too marginal for a basic PPL pilot (much of the time in the UK).
Without the IMCR, I would perhaps do 1/4 of my present hours, and my currency would fall to a point where it would be sooo easy to just pack it in altogether. Not to mention all the cancelled flights, which make flying with passengers very awkward.
Re the "proper IR" as some put it, there is nothing useful about the proper IR if the destination is an airfield without an IAP (which is true for most UK GA airfields) or the icing level is below the MSA (true much of the winter) etc. In the UK, the IR may be useful over the IMCR if you have a de-iced plane with a turbo engine, but then one is going to be above the clouds with no view. The IR really comes in for foreign trips.
Incidentally if a JAA IR costs £9000, that is cheap on the scale of what it will cost over the next 10-20 years actually making use of it. For starters, one needs to get one's hands on a decent plane (which is equally true for the IMCR) and the extra cost of that will dwarf the cost of the training. For anyone who is gainfully employed, the real cost of a JAA IR will be far more than £9000, due to the time spent on the ground school.