I cut into my first Caerphilly today. Not my first aged cheese -- I've made about 10 thus far -- but only the fourth to come of age, since required so much less aging than the others I've made. This one is 4 weeks old; I would have tried it at 3 weeks, bit I've been travelling for the past two weeks.
I'm very pleased with the results. As best I can tell from the descriptions I've read here, it came out just right: crumbly but not dry, salty, tangy. My youngest daughter was especially enthusiastic about it.
I followed the recipe in 200 Easy Cheeses pretty much to a T, but used 1/8 tsp MA011 and 1/16 tsp MD88 in lieu of Flora Danica or similar. Definitely a cheese I will make again, though next time I will cut back a bit on the brining time, or try making it from the recipe that Jeff Hamm has posted.
Pictures below show the cheese just before and just after cutting. The slight red coloration came from the wax -- yes, I know, not a cheese that needs to be waxed, but as I said I've been travelling abroad the last two weeks, and wanted to keep it simple for my daughter to look after, so I waxed it just before I left on my trip.