Hi Bill,
welcome on Trumpeter's U-552 club....
In my opinion, Trumpeter had done a superb model, regarding the interiors, that allow to do a superdetailing work probably impossible for other models, as Revell's one...
Regarding the "exteriors" ( hull, connint tower, deck, etc ), the thing is very different: in my opinion the model is really a bad affair; the worse error is that one of making the aft part of the hull in one piece of transparent plastic, deck and port and starboard side of the hull in one piece: that means that everything you do on one side of the hull to correct the errors in flooding holes, and other stuff, it will be visible on the other part ( that thing is valid for the entire transparent starboard side of the hull ).
Another bad thing is the needs of painting with primer the transparent part of the hull to correct the errors ( operate any modification on transparent part is for me almost impossible...); at least the entire port side of the hull would be in grey plastic, and not partially transparent as in the model....
Also make the deck in one piece with hull is, in my opinion, a bad choice, that complicates the work of detailing with photoetching's parts...
The one thing that make me angry, is the fact that, despite the graet availability of articles and studies, Trumpeter repeated the same errors of Revell's model....
So, I'm enthusiast of the possibilities offered by superdetailing the interiors, but for other things, it will be a real nightmare...
Cheers.
Filippo