Having tried most SB providers in the last seven years or so, my thoughts are:
1. They stop hunt
No, only as much as the real market does, in that there are always 'magnetic' levels with lots of orders being fired off.
2. The slippage took me out
In the real market this is always a possibility. In the SB world, where you're only trading their quoted price (as they all stress) slippage only happens because it's artificially added by the software when prices move quickly. They could instantly fill at exact prices if they wanted to, but then they'd lose out on their hedges in the underlying market (if they really have a hedge). IMO, they mostly add as much slippage as they think they can get away with, which, as Dante says, was too much in the case of VDM.
3. The platform froze
This used to happen a lot, especially with Fatspreads, but whether it was deliberate or not, they can't get away with it now everyone has fast broadband and decent computers.
4. They closed my account due to not liking me winning
Never won enough to find out(!), but they certainly try to make life difficult for those who trade short term (unless they lose, of course).
They accused me of cheating
I've never understood this, particularly the accusation that customers who have a faster price feed are cheating.
They only want losers
To maximise their profit, they'd be stupid if they didn't want a constant stream of new clients who almost invariably lose and don't need to be hedged. At the other end of the scale, it would be useful to have some exceptionally good traders who consistently win, and could be both hedged and shadowed.