This review is based only on the math of the card and not actual testing. Everything here is early theory and should not be regarded otherwise. That out of the way lets look at the card.
Breaker bay grid is a neutral 0 influence region. What does it do? its an "asset economy" card except its not an asset. This card gives you credits every time you want to rez another asset or upgrade in the same server. Bear in mind that ICE is not installed in a server, but protecting it, so it does not help rezzing ICE. It would easily be quite broken if it did. Installing this on an eve campaign will net you 5 credits when/if you rez that eve, or 4 in case of adonis. Added to that if the runner doesnt pay the 2 extra to trash this it is possible it can be used again for another campaign. So in this regard its similar to cards like hedge funds or restructure: a burst 4-5 credits, with added upside in that it may refire. The downsides are there to compensate though; the card can be trashed in HQ or RnD or the campaign can be cleaned and the upgrade left by the runner to repeadetly security test on. Another way to use this upgrade is with other upgrades like Ash or Caprice niseii. Bear in mind that it is impossible to use it with grids like sansan. Often you would only get 2 credits this way, but a lot of upgrades could be stacked in a server, and the defensive upgrades help ensure the bay can be refired. Using it this way is more comparable with drip econ, but does not leave weak remotes for security testing or bank jobs. Finaly it is just another card that can be installed face down in a remote and look like a tonne of other cards. Maybe you can get the runner to think it's defending your agendas, or it itself is an agenda, and make the runners decisions to run less informed.
Do notice the rez cost is reduced as long as the grid is rezzed. This is not blue suns wet dream, but picking up the grid and then the adonis/root later is still good value for 2 clicks.
All in all this seems like an economy card with high potential, but do bear in mind that it does nothing on its own. It only gives the 2 4 5 or whatever number of credits if you can rez something on it. The card is easily tournament quality even if there won't be a deck for it right away it produces a lot of money rather quickly if a deck can ensure it firing, and pays off sometimes almost as early as the transactions, leaving a mark for the runner to deal with before it fires again. The card is however not usable in any and all decks like hedge funds, jackson howard, daily business show etc.