I enjoyed it overall. I thought it was a bit lacking in comedy moments and was just a bit "too drama" for a prequel to the nation's most-loved comedy show, but it didn't spoil it for me.
A nice little "coda" to the OFAH story - but please, no more - don't spoil it.
Of course, this only worked if Trig in 1985 was meeting Rodney for the first time. It seems highly unlikely that one of Del's best mates would never have met his 25 year old kid brother. (Sorry, this is something I've kept pointing out to those near and dear to me for about 15 years...)