See I always go for pint glasses at a beer festival cos if you buy a half you normally end up with 2/3 of a point, especially if you smile nicely at the volunteers who man them. If you buy the half glass you automatically lose the possibility of extra free beer.
That said I am old and have been to many beer festivals over the years and it fills the TV with rage that there are so many pint glasses cluttering up the cupboards.