Does it have a positive or negative connotation when I say something serves as a reminder of ...?
For example ,
A photo album would serve as a perfect reminder of our friendship and the wonderful time we spent together.

This photo serves as a great reminder of the trip to Europe .

This scar serves as a constant reminder that I should be more careful when I cycle.

Does the sentences above all sound natural to native speakers? If they don’t sound natural , could you revise them for me ? I wonder if this expression “ serve as a reminder “ could be used both positively and negatively ?
Thanks a lot ! I appreciate your help !

Question

Does it have a positive or negative connotation when I say something serves as a reminder of ...?
For example ,
 A photo album would serve as a perfect reminder of our friendship and the wonderful time we spent together.

This photo serves as a great reminder of the trip to Europe .

This scar serves as a constant reminder that I should be more careful when I cycle.

Does the sentences above all sound natural to native speakers? If they don’t sound natural , could you revise them for me ? I wonder if this expression “ serve as a reminder “ could be used both positively and negatively ? 
Thanks a lot !  I appreciate your help !

Answer

Interesting. I think #3 is perfect. The first two are good but I’d prefer
A photo album would be a great reminder of ...
This photo is a great reminder of my/our trip to Europe. 
“Serves as” has a slight sense of doing something other than its intended purpose. 
My limp serves as a reminder of my years at war.
The local Starbucks serves as my office when I have to meet clients.
This is her Mom’s recipe. She makes it every Thanksgiving to serve as a reminder of her childhood.

Answer

They sound OK to me.

Acting as a reminder can be either positive or negative depending on the context.
But being reminded of something bad such as an accident can be good if it makes you more careful.

Answer

It’s stated it has neither a positive or negative connotation

Answer

I agree they both sound good and that it can be positive or negative based on context. Some even more negative examples might be:
The charred building served as a reminder of the horrors of the war. 
The museum serves as a reminder of the atrocities committed in the Holocaust.