I'm still rocking my original TF101 w/keyboard dock. It's taken a beating but still looks new. I just flashed Jellybean to it last night and its still doing well.
The thing the TF300 has over mine, besides the faster processor, better graphics, more memory,etc... is it's more rounded edges. It's nicer to hold than my original one (more squared edges, wider feeling). This one is more slimmed down.
The keyboard dock is the best design I've ever seen for any type of device like this. I like that you can completely fold it up like a small netbook, or simply detach the screen and take it with you as just a tablet. The keyboard works very well for banging out emails, connecting USB devices to it, and has the extra SD slot for either extra storage or moving things too/from it, though you can do that with a thumbdrive too. I also like that the keyboard types very nicely. It's slightly smaller than a full size,but also think of the micro size of this whole device vs a laptop or netbook. THe final nice thing about having this keyboard dock is that it contains an additional battery. I've been able to watch near an entire season of a 1hr show while one vacation once, while still checking emails, chatting with friends on IM and surfing the web and using google maps to get where I'm going. Absolutely excellent design.
The tablet itself is also a top notch tablet, there's no reason not to get this, say, over a galaxy tab or other model. Asus makes top shelf products are solid designers and back their products up (I've replaced many an asus item over the years with no hassle, motherboards, etc).
If you're wondering if you can replace a laptop with this? Well... kind of. I did this exact thing a couple years ago, replacing an aging sub-notebook.... while yes you can doing most of your businessey things on it (theres many office suites compatible with MS Office you can use, then the full suite of google products, etc)... you can even plug a full size keyboard and mouse into it (or a wireless, or a bluetooth, I even got my Wii remote to work on it)... you can make it as laptopy as you want... but... it still doesn't replace an actual full blown OS if you're a power user.
I do a lot of photography while traveling, and while I always took this with me instead of my laptop, I found that I still had to have my laptop when I went shooting (larger storage space, and you can't replace lightroom, which only runs on a full vs Android).
So this is a great little device, Ive had a lot of fun using it, for light to medium use it can replace your laptop easily... you won't even need to worry about finding a plug for it all day, especially if docked (BTW you can use the tablet itself until it gets low, then plug it into the dock, as the dock charges the tablet back up).
At this price, especially being the 32GB model, I HIGHLY recommend this.
Note all review comments were based on my 1st gen TF101. Same design, same OS, just not as fast as this one.