I like em.
The weight is not that noticeable, my bike still weighed a scant 22 lbs with Slime tubes.
When I added a front shock to the bike, it brought it up to 24 lbs.
I am getting a set for my cross bike as well, and I have them on the kids bike as well, they seem to do what they need to do.
EVENTUALLY THOUGH, on my MTB I will go tubeless, but for now a cheap alternative is Slime tubes.