sorry in advance for the wall of text
I bought a 32GB version several months ago, and my wife was using it so often that I picked up a refurb when there was an offer on ebay for one a couple months back.
based on my experience with the Galaxy Tab here's a few things to think about:
16GB and no expansion - while both of the Tabs I bought are the 32GB versions, I think I'd be fine with 16GB, because so much of the media I would normally store on the device I'm now streaming from the cloud. Netflix works on this and so does Google Music (which is free), and those would have been the biggest consumer of storage if streaming weren't an option.
no cell plan - this comes with wifi only, but as someone pointed out earlier, if you have a cell phone with the mobile hotspot, you can connect anywhere you have cell coverage. also, there are apps (like GrooVe Ip) that let you use your Google Voice account over wifi to turn your non-cell tablet into a VOIP phone.
top of the line now, but at the end of its product lifecycle - the Tab is arguably the best Android tablet, and perhaps the best tablet period, on the market right now, but there are some new tablets just around the corner that will surpass it. for example, the Asus Transformer Prime is spec'd to be thinner and lighter, but come with a quad core processor (versus the Tab's dual core), 32GB or 64GB storage, and new graphics capabilities - apparently for what a new 32GB Galaxy Tab costs today (around $499). the Transformer is supposed to come out in a few weeks but is pre-sold out in a lot of places. there isn't a whole lot of apps out there that would require the beefed up hardware - the only thing that comes to mind are some of the first person shooter games. for what I do - stream video, listen to music, browse the web, read the news, and casual gaming (angry birds, fruit ninja, etc) the Tab is more than enough.
ios vs android - I'm sure there could be a ton of discussion on this topic, but I think there's a few areas in which to compare.
1) apps - I think this is a toss-up, because while you may have a more diverse set of apps available for ios, all the major ones are available on both platforms. the big developers can't afford to ignore the android market because it's made significant marketshare gains since it was launched.
2) integration with google and gmail - if you already are a gmail or google calendar user, android offers the best synchronization for the Google applications. I've given up all the separate organizer software that I've tried over the years because my setup, I have one cloud-based solution across phones, tablets, and computers.
one related piece here - if you have multiple devices, android apps are licensed to individual users, not devices. so I can buy an application once and install it on all the devices I have. but with the appstore, I think you have to buy each app over and over again if you want to put it on multiple devices.
3) ios is simple, while android is open. ymmv for which is preferable for you, but in my case I like android's approach. apple has a relatively closed ecosystem that is centered on itunes. android also has a market, but there are others, like amazon and getjar. I think having more options is better.
4) peripherals - I think the ios devices (ipad / itouch) win here. there's a proliferation of android devices, so it's much harder for peripheral makers to target android devices - how do you pick? so sometimes, you have the device manufacturer as the only place to get things like keyboards, cases, etc. because apple is the only one making ios devices, it's easier for the peripheral makers to support, so the closed ecosystem actually means more choice, at least in terms of accessories.
but keep in mind, with the Galaxy Tab being the current top of the heap, it's easier to find accessories for it.
if you are worried that this is a refurb - small sample size, but the refurb I got through the ebay deal works perfectly. the only ways I can tell our two devices apart is that one is silver and one is white. on the back of the refurb, there's also a stamp that indicates it's a refurb.
bottom line, I think this is a great deal. if we didn't already have two of these, I'd probably buy another. I think the Galaxy Tab really is the best Android tablet on the market right now, and the price is good.