Well, by showing an S1 episode a S3 episode and a S5 you get to see 3 "eras" of the show. I do sort-of wish the selection of episodes had been better, and more than three. I mean they could've done "Yesterday's Enterprise" or "Best of Both Worlds" both of which would've been great at showing off the work they are doing. I can see picking "The Inner Light" since it's an acclaimed episode but Sins of the Father is an odd one to pick other than it showing off how well the make-up is going to hold-up to HD.
Yeah better episodes would have been nice, but at least they'll have perfected the process a lot more by the time they get to the good stuff.
Unlike last time, where Balance of Terror was the first one out, and ended up getting stuck with the cheesiest looking FX.