I can't really add anymore than what's already been said...
The guy is a NE broadcasting LEGEND... this is a tremendous loss...
I am not old enough to remember Don's days broadcasting Red Sox games... HOWEVER... like others who have already responded here, I too made it a weekly ritual of sitting down in front of my TV every Saturday at Noon for Candlepin Bowling... it was a sad sad day back in 1995 when Channel 5 decided to replace the Candlepin Bowling show for... ... news. :
A program that showed regularly in the Herald's weekly Boston television sports ratings (alongside the Sox, Pats, Celts and Bruins!)... and VERY inexpensive to produce (two camera men, a director and Don... oh yeah, and Ralph Stewart, the lob-line judge and referee! Wonder if he's still sitting there along side lane 21?

)
Who can forget Don's call of Paul Berger's 500 triple? (no sweat to accomplish in Ten Pin bowling, but very difficult to do in Candlepins!)
My favorite Don Gillis/Candlepin Bowling memory (that needs a bit of a set-up): I remember the amazing run the Gary Carrington had back in, i'd like to say fall of 1991, week after week Gary had returned as champion... it's been a long time but if memory serves me correctly he probably lasted as champ for two months... From the way he was bowling at the time I thought that he would be unbeatable the following summer (of 92) at their annual "Tournament Of Champions" ... well, the very week before the tournament that summer (and the last week of qualifying for the tourney) then-unknown Gary Casey came on the show and bowled I think a blistering
505 to become the number one seed... he would go on to beat Carrington a week later to win it all...
At the end of Gary's 505, it was Don with the call: Wow..... WOW!!!!!!!!!!!!!!!! Aren't you glad you decided to watch today? 8)
R.I.P. Don.