Yes, The Wire is the best show on television at the moment, and quite possibly ever. It's not a cop show, though, despite what you may think. It's actually a critique of urban America, and the different institutions that are failing the public they are supposed to serve. Each season examines a different facet of society as well as building upon what was already covered in the previous seasons:
Season 1: the legal system (the police department, prosecutors, and judges)
Season 2: organized labour and the employed poor (the stevedores' union)
Season 3: politicians (Royce, Carcetti, and Gray)
Season 4: the public education system (the four kids, Prez and Bunny)
Season 5: the media (Gus, Scott, Alma, et al.)
My predictions for the last episode:
McNulty and Freeman get away with it. Too many people have too much riding on the bogus serial killer story for it to be exposed as a fraud. Rawls and Daniels can't speak up lest it look like they were misspending all the money City Hall was throwing their way to catch the serial killer. Carcetti needs the Marlo arrest to stand so he gets his much-needed drop in crime, not to mention he latched onto the theme of homelessness to fuel his campaign for governor. The Sun can't expose it because they're trying to win a Pullitzer based on Scott's reporting of the story (and his phone conversations with the "killer").
However, McNulty is stricken with grief and kills himself. One of the last scenes will be at that Irish bar for a policemen's wake with McNulty's body on the pool table. Lester ends up demoted back to the pawn shop unit as Daniels tries to quietly make the whole mess disappear.
Michael becomes the new Avon/Stringer/Prop Joe/Marlo and ends up running the West Baltimore drug trade. Even though Marlo falls, the cycle begins anew.
Bubs kicks his habit in one of the few positive outcomes for any character, but this is contrasted with shots of Dukie becoming a heroin addict.
Gus exposes Scott's fabrications, but management at The Sun won't take appropriate disiplinary action because they want so badly to win a Pullitzer. Gus resigns in protest (or accepts a buy-out).
The Bunk is still The Bunk.