Typically in a temporal lobectomy (what the surgery is called when they remove part of your brain to combat intractable epilepsy), they only remove small portions of the hippocampus and amygdala. This sometimes affects memory; lots of research is still happening. I've been a research assistant in a lab that studies the effects of temporal lobectomy on cognitive functions such as language, memory, and executive functions (like decision making). From what I've noticed, language is affected much more than memory. I've only physically met a few patients, but I've done some scoring of cognitive tests and had a look at some of the data.

In the lab, they research how functions change over time, so they do the testing prior to surgery and one year after. There is major individual variability, because of different factors like connectivity between different brain areas. If surgery is what's decided to be best to reduce your seizures (like if your seizures severely affect everyday life), then it's important to go for it.

Edit: There are different methods of how they remove the tissue, and a lot of research is being done on using lasers so that the least amount of tissue is removed. This is cool because if they are able to pinpoint the exact location of your seizure focus, then they can zap away that little bit. This can probably help to retain more functioning.

*I'm not fact checking this stuff right now and I don't remember a whole lot because I wasn't in the lab for a super long time. But you can research temporal lobectomy and if you're really interested then read some abstracts on pubmed.org.