My girlfriend and I have recently ordered a 100% memory foam mattress from Keetsa, king size.

Generally I've only read positive comments from friends, etc about memory foam mattresses.

The one big possible negative is, honestly, other bedtime activities, given that memory foam beds don't have the same spring and bounce as coil mattresses

Anyone have an opinion on this?

Some things I've read online say it could be a major change to your bedtime sex life, and some people say that it's a minor adjustment and to not worry about it.

We slept on innerspring mattresses for the first thirty years of our marriage before switching to a memory foam and noticed not a single issue with regards to sexual activities. Being more comfortable meant that frankly we were more comfortable! We ditched the memory foam for other health reasons and are back to our old innerspring, well all non-sleep activities are still in full fun/function and the mattress had no impact.