Being the pessimist I am I actually thought it would go the other way, but would fail miserably due to it pretty much being impossible to actually prove if you don't look at every file piece in detail then assemble them and even then it wouldn't work due to encryption being used on most systems these days.
This is good news and here are some reasons
1) File sharing as a concept isn't illegal
2) It would just be a waste of money that could be used far better on crimes that are actually effecting the majority of society for instance selling of pirate CDs and DVD's which are far easier to track and will remove part of the problem far more efficiently
3) If you are really taking the piss your ISP will just cut you off for using too much bandwidth
4) If they have to screen for songs, films, pictures, games ect should they not have to screen for child porn, bomb making websites, terrorism websites, pretty much anything that is illegal that can be done over the internet that is far worse than sharing some files, this should be done, but can't be in any effective way either, but it would have been a slippery slope.
5) The music industry should just stop being a bitch and fixed there fucked up business practises, they claim it is for the artists, yet it really isn't many examples have come to light of artists going, eh....don't really give a shit if people download the song it will spur some to go out and buy the album and many to come see us live, and normally going to see a band live costs as much as an album or more and this is where their revenue comes from.
If the music industry had adapted to the internet 5-10 years ago instead of in the last 1-2 years maybe they wouldn't have been so ass fucked by the fans of music.
6) A good general point not to do with file sharing is this has stopped the whole screening of everything culture that is coming into place, everyone say, oh it is only a problem if you are doing stuff wrong, but fail to see the point that one step always leads to another and I would rather stop the first than the 6th, at least the whole "It is for national security none of you are safe in your homes" crap isn't being taken seriously any more.
On bad points of this decision
1)...eh the music industry might actually have to adapt...which is bad for the music industry I guess
2) Look at 1