There were just a very few moments in the second season of The Wire when I thought an acting choice or a camera shot was un-subtle, which is quite a testament to all of the other perfect moments that made up the show.
I didn't really expound on the show when I finished the first season, because I kinda figured everyone in the world but me had seen this show. Since recent conversations seem to proven that untrue, I'll summarize for you. The Wire is set in Baltimore and each season follows a single criminal case from investigation through whatever arrests and charges are made. It's not a mystery, because we get to see things from the criminals' perspective just as often as the cops. Both sides of the law are filled with politics, drama, personal issues, and lucky/unlucky breaks.
The first season delved into the world of a mid-level drug dealer and his crew. This season expands the scope to include the smugglers who are supplying the drug dealers, as well as smuggling human traffic and stolen goods.