I think they are definitely worth the cost. So good for internet browsing and i way prefer it to a laptop or desktop. If you get an iPad with 3G then there is a monthly cost, it's sort of like getting a phone contract, you get a SIM card with a certain amount of Internet usage on it depending on how much you need to use. In my opinion it's pretty pointless to get a 3G one when you look at the extra cost. It is much slower than a wifi conn room so you would use the wifi at home and if you have a phone which can access the Internet then you can connect the iPad to your phone's 3G signal ( this is called tethering) meaning you can still go online while you are out without paying for a 3G contract for the iPad. Sorry for the long message. Hope this helps!
If you are likely to use hundreds of apps and do lots of downloads I would get more than 16 gig. I have this and according to my settings it's nearly full. Think photos use up lots of space? No contract here but I tether it to my home and other friends houses via their broadband service and use my phone for roaming Internet. Man at PC world said buy the ipad 2 not new ipad as you really don't notice the extra pixels unless you are a tech lover and not worth the extra £s. ipad is very nice though and I love it.