Bunion surgery is generally a very safe procedure. Risks will include surgical and anesthetic risks, and usually is between 1-2%.
Short term surgical risks include bleeding, infection, neurovascular damage and very rarely fracture; and anaesthetic risks include heart attacks and strokes/ brain damage. This is however very rare, and usually in the older folks with multiple medical problems.
Long terms potential complications would include recurrence of the bunion (though usually not as severe), and sometimes a reverse bunion (or hallux varus, where the big toe points inwards instead of outwards).
Example of a severe Hallux Valgus with overlapping and underlapping toes:
