Oh God, so many. For one, I had no idea so many people hated "I, Borg", that's among my series highpoints.
I can't stand that episode because it humanizes the borg and makes you feel sympathy for them. It's the jump the shark moment for the borg. Picard should have followed through with the virus. The borg were not a conventional foe that could have been dealt with like the Romulans or the Cardassians. He should have wiped them out.