I find it OK. I like the fact that I am in control of my own space - no-one else can recline back into my face. If you want to use a laptop then it's great. To the specific questions.

1) Yes
2) It deceases the knee room more than the leg room - you can still put you feet under the seat in front. If your legs are very long then yes it decreases the leg room.
3) Much the same
4) No. On balance it's an improvement on the old one.