Part of my post from other board.
Not, its not. Do some math. D2 had 88 slots per character and You can have 10 of them, so 880 per account and You could have multiple accounts, in D3 You cant because of BN 2.0.
Now runes, there are 5 type runes for every skill and every character has 24+ skills, so You need 120 slots just to store runes of one lvl [there are 7 of those!] for one char to have different builds.
Now gems, there are 6 type of gems and they drop only to lvl 6 and there are 14 [dont remember exactly] levels of gems and to make higher lvl gem You need 3 lower level.
http://img714.imageshack.us/img714/8822/gemlevels.jpg
Most items takes 2 slots.
There are so many things to store that its not even funny. 350 slots its less than 4 character slots in D2!
Just count how many You need, different gems [high level to use/sell or low level to craft higher ones] and runes for different builds and characters, low level pvp gear, low lvl pve gear, high lvl pvp gear [for couple of builds], additional items for current build, items for sell, uniques/items You like or for new characters and
all of that in 350 slots, period, You cant make new account, new char, new mule, this is it.