Over the top,
Why won't she stop?
Once she used to be funny;
Now she's here for the money.
All that she does
All that she was.
When you see
You'll never know why Lucy is here.
I'm always glad when any show gets season sets -- every show has fans, and fans deserve the chance to get complete sets -- but the best-of set is enough for me. And yet I've always liked the concept behind Here's Lucy; her kids were both good-looking and had potential as actors (Lucie became a fairly successful stage actor, and Desi Jr. played the groom in Robert Altman's A Wedding). The Lucy Show suffered from not having the kind of solid, believable relationship that she had with Desi on the original show, the kind of thing that could give some kind of emotional foundation to the comedy. The presence of her kids could, theoretically, have brought that back, but the show wasn't written that way; it was the same show as The Lucy Show, only with teenagers.
That was enough to make it a top ten hit for the first few years, and it's a tribute to Ball's star power that she was able to keep her ratings so high that CBS couldn't cancel her, even as they canceled all their other older-skewing shows.
There's also a theory among some Lucille Ball fans that Milt Josefsberg, the head writer of Here's Lucy and the later years of The Lucy Show, was a jinx (despite his success writing for Jack Benny); not only did Ball's shows go downhill after he joined, but he ran Laverne and Shirley in the season where they moved from Milwaukee to California, and was a big presence in the later, worser seasons of All in the Family (and Archie Bunker's Place). I'm not sure how much of this can actually be blamed on him, but he's arguably the Ted McGinley of comedy writing.