I liked the idea of a tablet but really you have to pay a decent amount of money to get anything worthwhile, that part I didn’t like.  It didn’t make sense to buy something that wasn’t supported or had glaring faults that were difficult to overlook.  These are the things I looked at regarding before buying a tablet:

1. CPU speed – if the device doesn’t have a viable CPU, that being something that is appropriately clocked (>600 mhz) or one that is older technology and poorly supported then the device will never be responsive
2. Memory – if the device doesn’t have a decent amount of memory a lot of the CPU time will be trying to manage memory slowing the device down (typically you’ll want more than 256mb)
3. Screen – if the device has a poor screen, difficult or impossible to read under certain circumstances and lighting or if the screen is not capacitive or does not allow for multi-touch then your choice for software may be limited or using the device may be difficult in many situations
4. Support – if there is no after-market or ‘hacking’ enthusiasts actively discussing or improving the device then it’s shelf life may be limited beyond what the device ships with.  Typically if there is no forum discussing your device on XDA or SlateDroid then it’s safe to say that you will get no support beyond what the device ships with.  Do NOT buy a device in hopes that it “may” get an OS improvement or has the specs to run a new OS / features because if no one writes the improvement for the device it can never had the improvement.

In many ways item #4 is the most important.  Hardware is only ever as good as the software running on it.  You can have a very advanced tablet in terms of memory, cpu, screen but if the software not well-written for it it’s response and use could be very limited.  In the same breath you can say even if the device has some glaring faults on the hardware side good software and good support can often help eke out the most from the device given it’s limited hardware.