I don't think slashed is too dramatic a word for today's announcement.
From next year CGT allowance goes to £6000 then down to £3000 the following year.
Dividends go down to £1000 then £500.
These allowances have been a great help in the movement of holdings to an ISA, which is going to be much more difficult now.
Mind you.....a) It could've been much worse (and may still get worse) and b) While we may moan about tax on inflationary gains not 'proper' gains etc. Nobody's going to have much sympathy for us investors.