Still not enough I had a storage kid filled up and my INV was full. I hope they put in the sort feature b.c it was horrible looking for ingredients.
Yeah, it's not really enough for crafters and not being to easily send items over to a mule for storage isn't helping either. 100 sounds great since your equipment's tied up in 400~ armory chest slots but the sheer number of monster and harvesting/mining/fishing items is going to end up being a big thing.
The retainer's 175 will help some and supposedly they're going to set the "safe" in your home/inn around 200 which will help more. More than likely I may just create 2-3 mules and say "This one is cooking mats, this one is botany, this one is mining, and this one is misc." or something like that.
Yeah, I started to run into inv problems in P3, but a) I didn't get around to getting my retainer, which would have helped, b) Add housing in (yes, expensive, but as others have said there isn't a huge requirement for gil usage at this stage), and the storage shoots up, and c) I was dabbling in a bit of everything (mining, armourer, GSM, alchemy, cooking, blacksmithing). Yes, there may be inventory issues, but they won't be anywhere near as bad as XI. Sequestering armour & crystals in their own inventories is a good move too.