[amatix]

You can bash, as long as it's factual: "X is more expensive, has a lower resolution, smaller area display, shorter battery life, and is heavier than Y. Buy Y!". They're all facts. But you can't say (in the rest of the world outside the US anyway) "X sucks because it's slower than Y. Buy Y!", unless you have big brave lawyers or X is somehow slower on every independent factual measure.

[Someone]

I think you need the 'sucks' part to talk of bashing. http://en.wikipedia.org/wiki/Bashing_(pejorative) seems to agree:

"Bashing is a harsh, gratuitous, prejudicial attack on a person, group, or subject."

Also, I think you are not ever allowed to say "X sucks" in the EU because that is an opinion, even if X is somehow slower on every independent factual measure and if X is 100% equal to Y in every other quality (price, looks, weight, etc)

For example, a slower car might be more appropriate (= suck less) for people with slower reflexes, a slower mobile phone might stay below your data limits easier, a slower restaurant might give you more time to contemplate about the meaning of life, a higher price might make a product more attractive.