700 Grab points for 160 miles from now until 30 June 2019
Grab is currently running the Grab Singapore Sale now, with an array of offers and discounts between 24 May and 31 July 2019.

One promotion is a 50% discount on the number of reward points you need to redeem for Krisflyer miles.
Between 1 and 30 June 2019, you can use only 700 Grab reward points to redeem for 160 Krisflyer miles. You can redeem as many miles as you want.
Is it worth it?
In short: yes.
Grab points are usually best used for discount vouchers on Grab rides. Usually, you will need 1,900 points for a $5 voucher, and that gives a 0.26 cents valuation to each Grab point.
Krisflyer miles are valued at about 2 cents a piece, so using 1,400 points for 160 miles will mean forgoing $3.68 (worth of Grab credits) for 160 miles, or 2.3 cents a mile. This is higher than what you should be paying for.
However, at half price, the cost now goes down to 1.15 cents per mile, which is excellent value when buying miles.
This promotion is also well-timed, given that Grab points usually expire in June and December, so it will be a good time to finish up all your expiring points.
The process is painful

On paper of course this sounds like a terrific deal, until you start to redeem it. While there are no limit to the number of time you can redeem this deal, note that you will have to key in your details each time and wait for the conversion to take place before you can make another redemption.
So if you are intending to make use of this promotion, start now and slowly make your redemption throughout the month.