I have owned a wood case for my 5s that I have used for over a year. I got the fully wooden case from Grovemade.com and inspite of what the previous poster says, the quality is excellent, the "holes" for the speaker were absolutely NO HINDERANCE, and the "line" for where the case comes apart is only distracting if you have a blank case.
The problem I have now is that Grovemade.com is only making BLANK cases now and I still like the customized design on the back. Grovemade quality is the best I've seen, but without the ability to customize...I'm looking now at Carved.com. They are telling me that they will soon offer customization on their traveler cases (wood backs with rubber bumpers) and even customization on their full wood cases.
As the wood ages...it definitely gives the phone CHARACTER! In addition, I plan to skip the next cycle of phones from Apple because I love my iPhone 6 Plus so much.
Here are two photos...the first one is iPhone 5s case that I used for more than one year...this is bamboo and I "conditioned" it with BLACK SHOE POLISH (kinda like a stain)...loved that case. The second image will be the one I use on the Carved.com iPhone 6 Plus case when they start allowing customization of the case.
In summary...the "sound holes" of the wood cases does not effect the sound coming out. The split line is a matter of taste...some it bothers and some it doesn't. No one ever said anything about the line on my phone because of the design.