We bought 2 of these for my wife and I over the past weekend (for slightly more, but they were new). In my use so far, I can tell you that it works well and the screen resolution is nice. If you are planning to type much of anything - get the keyboard and get the right one (one matched for this product, not something close). I would not bother with the one I have seen in the comments - if it doesn't match, then just get a bluetooth keyboard for a lot cheaper. For some points of comparison (i.e. the major differences) to other models that are similar:
TF700 (also from ASUS)
-Faster clock (1.5Ghz instead of 1.2Ghz on TF300)
-Brighter screen (can be used outside)
-More durable screen (at least allegedly)
-Cost of about $100-$150 more.
Nexus 10 (from Samsung)
-Newer Exynos 5 processor that is faster
-Extremely high screen resolution (higher than newest Ipad)
-No keyboard docking
-5W charging over USB
-$400 (and won't be on sale anywhere for a while)
I should note that the TF300 uses a custom cable to do the charging, but this allows it to charge at 10W, which given that the batter is a 22W-hour battery, means it charges from zero to almost full in only a couple of hours. The keyboard has an 16.5W-hour batter that can "feed" the tablet, so it charges in about 1.5 hours. Also, this has the Tegra 3 processor (not the Tegra 2 or other last generation processors), so it is still the "current" stuff. I would not buy anything (personal preference) that did not have a current version of processor.
Finally, we looked at the size issue when buying this, and you will end up with around 12GB of space for you to use. Micro SD cards are fairly cheap, so if you really need more space for media (I don't think I would put apps on the plug-in card, but media is the only thing that really sucks up space), just buy one and plug it in.