man im wondering the same thing. ive read a review in a musiciansfriend magazine and they seem like a steal for the price. obviously theyre just for getting stuff down right there so you dont forget it.
well thats true, but the backtrack is designed so you just plug in your guitar and play. it's made so you can basically save your ideas and cool licks when inspiration hits. it's kind of a niche product.
Gear :

Gibson Les Paul Special
Fender Koa Stratocaster
Korg Pitchblack
Dunlop 535Q Crybaby Wah
BBE Boosta Grande
Fulltone OCD v4
EHX Russian Big Muff Pi
Vox Night Train
Egnater Rebel 112x Cab
Marshall Class 5
hmm...seems the old one isn't being sold anymore but the new GX with Pod-Farm is selling at $100 which is quite high... The old GX sold for around $60 IIRC

With the interface prices up for line6, you may just be good with the portable product...

Old GX:
you install gearbox which is the software and driver in one...
you plug it into your USB port and it powers up
plug in a guitar
launch Gearbox
set the inputs, and then amps
play a guitar
monitor out the back of the interface with headphones or PC speakers.

Gearbox isn't a recording program, you will need to buy or download a free sequencer to record. audacity is popular for small basic setups..I use it for ideas. Reaper is about $70 and you can do a lot more with it which is nice.