At the risk of repeating what has been said... IMHO they are good until something goes wrong. Then they're not so good.
However, to be fair that can be said of a lot of other companies...
My view would be that they are good if
(a) you're looking to buy something that's fairly cheap and reasonably well-specified for the money
and
(b) you are happy to fix most problems yourself
If you like the security of having help if something goes wrong then go elsewhere - but remember that the support is factored into the asking price, so that 'bargain' deal may come at the expense of useless tech-support later on.