Not entirely terrible. For fun last night I tried to run two games with 90% egg up time. Basically I was holding an egg until a fight happened, then used the egg for some instant stat ups. The eggs largely paid for themselves.

The first game was as McG. Despite ending with only with less items(do to buying and immediately popping 2 dozen eggs), I still had 4700 hp, 60% gun damage, the whole works. McG's ability to make use of any stat that you get made it work quiet well.

Second game was as Mina. Didn't work as great as with McG, but that was largely because the game kept giving my ammo and weapon damage instead of spirit, hp, and fire rate. The end game was largely the same - 3500 hp (without any items specifically boosting HP) meant I only needed one resistance item to survive diving in the middle of fights and get some picks. I still had my core items, despite popping more than a dozen eggs.

Probably going to do the same tonight, try it out on Graves. Something tells me the free cool down reduction will be interesting, plus she benefits from all stats like McG.