Think the science was beyond shakey.
A three day old bite from a peach is enough to supply all the fresh Vulcan DNA to create a vaccine and not a bat in sight. I suppose if it had been a day fresher they could recreate a fresh T'Pot?
And the virus manages to create a genetically generated map to make them return home?
It was a tried and tested plot, not just Genesis, but anything involving Borg assimilation requires major genetic restructuring of the infected person as well. In the science stakes, I think I would give the nod to the Borg for believability.
But actually my largest quibble is with Archer's decision at the end. The race is dead, man!
The only way to resurrect it is to destroy another race. Even then it must evolve into something intelligent again, where upon they are even less likely to be original.
Which all goes to highlight the dicotomy in the treatment of the Borg. Resist a Borg recrutment attack, but happily roll over to become another bunch of foreigners that are definitely dead!
And of course we have the required T'Pot/Trip neck massage. Makes the score T'Pot 3 Xindi 1