Welcome aboard.
Unfortunately, the unmodded SH5 resembles more of an arcade shooter than a simulation. In other words, if you want the most out of this game, grab mods.
Sober's Mega Mod (
http://www.subsim.com/radioroom/showthread.php?t=192374) provides a comprehensive list of most of the mods that you may want. As for individual mods, the top three mods you'll actually want to start with are TDW's New UI (
http://www.subsim.com/radioroom/down...o=file&id=1582) which provides a comprehensive interface suitable for a simulation, IRAI (
http://www.subsim.com/radioroom/down...o=file&id=3866) which enhances enemy AI and allows planes to actually attack you, and FX Update (
http://www.subsim.com/radioroom/down...o=file&id=3867) which adds large numbers of new effects for enhanced immersion and allows fires to actually damage a ship overtime.
There are many more mods that I use such a Real Sink, One Ship One Torpedo, and Historically Accurate German Flags. Mods really change the game but expect to restart the campaign numerous times.