The Solo is intended to be an extremely simple product that anybody can set up and use. I think WHF's 'against' of limited inputs is a bit unfair as the intention isn't to plug all of your sources into it - your sources all plug into your TV as they normally would, so there's no unplugging products and having to wire them back up again. All that is needed it to place it under your TV, plug it in the mains, connect it to your TV's analogue or optical digital output, and you're done!
As for sound quality, sure you can get a pair of speakers and an amp that will probably sound better. but it is clearer, fuller, and more intelligible than the TV's speakers, which is the whole point of the product. Its either this or a cheap Yamaha sound bar.