I think this is an excellent start to the second season.
The plot is mainly concerned with updating us on the lives of previously established characters whilst introducing new faces and locations. I think this is done very effectively, aside from one or two very unsubtle exchanges of exposition dialogue.
I am intrigued by the new waterfront locale and characters. Shifting the focus off the tower blocks to another area is thematically a great move by the writers.
The scenes set dockside are all superbly made. It shows the decay and decline of an industry, but also the remaining heart of a working class culture in full swing during the scenes at the dockers' club. In the same breath characters like Frank, Nick and Ziggy all make compelling first impressions.
For me the real high point of the episode are the scenes involving McNulty. It is a very different role for the character, but what he does is typically Jimmy McNulty. It also brilliantly connects the main characters from season 1 to the new setting. It is, for me, one of the (darkly) funniest plot lines in the show. Speaking of humour, there is also plenty of great banter between Kima and Herc, Rawls and Landsman, and naturally Bunk and McNulty.
In typical Wire fashion, 'Ebb Tide' presents strong parallels, particularly between the working classes of the police force and stevedores. Lost evidence - shipping containers, instances of bribery, epic drinking sessions, and the senior figures connection to the Catholic Church.
There are some intermissions involving characters from the Barksdale crew that give a good continuity to the overarching narrative of the show. The scenes involving Bodie, are remarkable given what transpired during the first season. You should hate this character, but the writing is so clever and J D Williams conveys enough humanity that you cannot help but stay with him.
The tone of the episode is (for The Wire) reasonably light until it hits you with a brutal final scene that brings it crashing down to reality. The timing of this is very effective and hooked me into wanting to know what comes next.
All performances are wonderful as ever with the standouts for me being Chris Bauer, Dominic West, Wendell Pierce, J D Williams, and Idriss Elba.
The cinematography and editing, as ever, is great, particularly during the waterfront scenes.
For me it is a 9.5/10 but I round upwards.