In the previous beta-phase, I reached the level cap (35) only with earned prestige points, had build four VII subs, lost three of them by depthcharges and all my credits stayed untouched. I never needed credits for better technology or better torpedos, the old torpedoes for prestige points made the same job.
Now for the current beta-phase, BlueByte gave me 150.000.000 credits for the success in the previous beta-phase, so I can test the shop-system extensively and buy me the most expensive torpedoes ...the game is now almost too easy ... lost a sub now, no matter I can buy several new ones.