Are there any risks or side effects to multifocal lens implant surgery?

Multifocal IOL risks. MIOLs have many advantages: improve the reading, distance, & intermediate vision in the vast majority of patients (assuming macula, optic nerve, brain are functioning normally). Halos, glare (usually improves with time), need for reading glasses/distance Rx from residual astigmatism biggest risk after MIOLs aside from general surgery risks.
Minimal. Just like any procedure there are risks involved. I encourage you to read my book, pi in the eye, available on amazon.Com to give you more information before you go and have a multifocal lens implanted.
Yes. Just like with any cataract surgery procedure, there are risks associated with the surgery such as infection, bleeding, pain and loss of vision. With multifocal implants these risks are no different. In addition to these risks there are common issues with these implants such as "halos" around lights or neon signs at night. This is usually an issue with the nonaccomodating implants.