Ended up re-watching the first 2 seasons of this and nearly all of original Lost in Space (ok, it was mostly background noise) before finally getting around to season 3.
Being someone who has listened to and watched every episode of the original series probably more times than anyone else living (just worked out that way.. it wasn't planned) I would say 2 things right off..
First thing is that I like that they made something closer to spectacular than not. I mean, they could have just used the name in the title to sell some episodes but they didn't. They went all out with story and eye candy.
Second thing is that it would have been nice had they given more nods to the original series. If you can manage to acquire a taste for the original Lost in Space then you see that the best thing about the show is the relationship of the characters. And they're in Space. Kinda like with original Star Trek. They chose to rewrite a lot of that chemistry from the original Lost in Space. They did give some nods to it at the end. Like when Wil and Smith or the Robot go off on their own and no one else knows what is going on while they are deciding the fate of the universe. That was the theme of nearly every episode of the original series.. Judy was her mom's right hand and Penny was daddy's little girl - they gave that a nod at the end. OH and Don got in a fight he couldn't possibly win and was knocked out with the whiff from a punch. Finally. lol. That was Don's job when he wasn't smooching John's butt, in the original.
They have original Wil (Billy Mumy) in a couple of brief cameos as Dr. Zachary Smith. I think original Dr. Smith would have liked that. They weren't brave enough to try to duplicate the original Dr. Smith. I don't think it's possible.
They use a tiny amount of the original music which came from someone you might know if I remembered his name right now. John Williams?
Great special effects and characters. Action. Robots. Space. They didn't have to name this series Lost in Space for it to be good but I imagine that does help sell it and I don't mind that they did.