I bought one about 4 months ago to use while traveling for work. Mine is a cheap €129 (less than $200) import from China that looks almost exactly like the Samsung Galaxy. Compared to the Galaxy it lacke the camera and telephony features. To say I'm happy with it would be an understatement. It uses the Android OS and while it is not the latest, it does work. Applications are available by the thousands. It does have a micro SD card slot, a mini USB port and built in WIFI. So far I've connected to the USB a webcam, external HDD, memory stick, ethernet adapter and one of those USB Cell Phone Internet sticks. Everything worked flawlessly. When on the road, I use it for Internet access, music, movies, E-books and Skype. At home my kids like to use the Youtube application it came with. The battery will last about two hours when watching a movie or reading a book. If you are doing music or other things where the screen can be turned off it will last a lot longer. I only have two complaints. The on screen keyboard is somewhat troublesome to use and scrolling takes some practice.
Am I going to recommend that you buy the same one I have? No. It is from a small German company that specs pieces and then imports them from China. Here is what I do recommend. Do a search for Android and look at the applications available. Figure out which ones you would want to use and pay attention to which version of Android it requires. Then you can go look for a tablet that meets your needs. I highly recommend the USB and micro SD slots. I wouldn't pay attention to the brand name since they all come from the same place anyway. Size may be important but I like my small one since it is easy to carry around and use as a book reader.