I was wondering if the campaign is truly dynamic (game world reacts to your actions) or perhaps more simply a string of randomly-generated dynamic missions. I can live with Germany losing the war in 1945 (historical fact, I'd feel uncomfortable if the actions of a lone U-Boat could influence the outcome of WW2 in the game).
I think the campaign does model (or at least cleverly simulates) the reaction of Allied forces to your presence. While it's still early on in the war (I just completed my 5th war patrol, time is now Jan 1940), 2 incidents reinforce my belief:

Thus far my patrols have been in the North Sea area and all assigned patrol zones have been in the region E of Scotland/NE of England. (Although my 2nd patrol had me patrolling fruitlessly off Norway I eventually made my way SW.)

1st instance:
I was going after a lone merchant vessel some 100+ miles E of Hartlepool. In my Type II A I had surfaced to do an end-around in order to get ahead of my target. Unfortunately I grew careless and was spotted presumably by the merchantman. He must have radioed for help since over the next hour or so I was attacked separately by 2 pairs of Hurricanes. I sank the merchant and crept away submerged.

2nd instance:
Back in my normal hunting area, this time in a Type VII B. I had a particularly successful patrol (by my standards anyway) and had sunk 5 merchant vessels of various types all within an area in the vicinity of NE England. Then off the E coast of Scotland I encountered a destroyer which I managed to sink. Reversing course back into my normal hunting grounds I encountered two more destroyers, one within visual range and one more further out via hydrophone. After I sank one I decided to make my way back to base as I was down to my last torpedo. Along the way I picked up, either visually or by hydrophone, at least 3 or 4 more warship contacts, all separate bearings. It could only mean (at least I like to think so) that the RN had despatched a number of DDs to try to hunt me down.

This leads me to think that within each patrol anyway, the AI does react, in a believable fashion, to your actions.

Anyone else like to share their experiences?

You gotta ask the question....... Does it feel real? If it feels real then it must be real imagined or not!

I had to start a new carreer after building a new PC. I installed patch 1.2 yesterday and I noticed some thing I had not before. I had A/C chasing me after waiting on a C2 to sink for only about 30 min game time. I then submerged and resurfaced many many miles away at dusk. I was imidiatly jumped by TWO planes. Never had that happen with the first patch and 4 patrols.

It feels real to me!

This is probably the best dynamic campaign I've ever played. Although I really enjoyed Mig Alley's dynamic campaign.

The only improvements I can see would be to simplify the crew rotation. Add wolf pack stuff and resupply.

Multi-play I would like to be able to have two players in the same boat and play a dynamic campaign together. With crew management, navigation and manual targeting I think there would be enough to do for two players.

I picture one player using the scope and driving the boat giving information to another player who puts it all together for a solution and controls the crew management.

Now that would be cool.

My experience has been that the game does model some kind of "call for help" function for the allies. I have run in to this several times and have learned that my successful daytime surface attacks SHOULD always be followed by an hour or so below the surface to get the heat off of you.