First of all, the series rules are the same in SOPAC and Bomb Alley -- so, read the rules and check out my research and comments on them here: SOPAC Rules corrections/clarifications/enhancements.
There are some minor changes to the tables. You also might want to take a look at the errata and my suggested additions for the SOPAC tables here. Here are the changes in the tables:
I was also disappointed to find this mistake is still present in the battle board of Bomb Alley (present ever since SOPAC, the first game in the series):
What is even more amazing is that on my battle board, the movement tables are completely missing! There is a paragraph talking about them, but they are nowhere to be seen. I'm not sure how something like this gets overlooked...
I don't like the silhouette backs of the ship counters in Bomb Alley. I don't know why it was done this way (as compared to SOPAC), but I liked using the backs on SOPAC to represent ships missing some of their guns. But apparently other players like to use the backs for fog-of-war battles.
The maps are nice and big. Unfortunately, I can't find any good way to line them up together. You seem to have to choose between lining the numbers up properly or lining the land up semi-properly.
Please send any and all comments to me at firstname.lastname@example.org.
You can find all of the information I have on Bomb Alley here.