The biggest joke is the 16gig size. Too bad apple couldn't eat $5 into their profit margins to make the entry level 32 gigs instead of 16 gigs.
I have a 16 gig ipod touch and with SOME of my music and a couple of apps it's full to the brim. I have NO room for photos, NO room for any video, and I have to pick and choose my apps (especially big ones like games) and constantly delete music to put new stuff on.
32 gigs would be the MINIMUM to make this device worthwhile, with 64gigs being comfortable. If I were to have an ipad I want all of my photos on it (several gigs from iphoto), I want a good amount of my music (maybe only 5-10 gigs, it's not an ipod so I probably wouldn't put my entire library onto it), I want a good amount of video, and lots of apps. I could see myself filling a 32 gig ipad to the max from day 1, and then having no extra room after that without going back and deleting something (which sucks). I want to take this with me instead of a laptop when I don't have to do work, so I can show pictures/video/music to friends and family. What good is it if the storage is too small (16 gigs) to actually bring any of my content with me? I'll have to bring my laptop with me if I want to get work done AND if I want my data with me, which makes the ipad useless.
I'll wait till gen 2 when the bugs are worked out, there is a huge library of good ipad specific apps, when it gets an updated and tweaked OS, a front facing camera, more power, and REASONABLE storage.
I think at gen2 this thing is going to be revolutionary for one main reason, the apps. As all of the critics have pointed out this is just a big ipod touch, so it needs a big library of kickass apps from creative programers who can think up awesome ways to use the ipad that make any other sort of computing seem like a joke. Right now there is none of that, but we're starting to see a glimpse of it's potential.
It will be a year before any of this is established, and by then the 2nd gen will be SO much better in terms of hardware.
All of the 1st gen ipad owners will be twiddling there thumbs for a long time until some really great polished apps start to come out and people get more and more creative (not to mention the bugs being worked out). I'll just twiddle my thumbs with my mbp and wait until the real ipad is released next year.