5 - 30 minutes
The HD (standard HD that came with the laptop) that I originally have was getting too limited with storage space and I really need it to be upgraded with bigger storage volume, so I went with 1Tb SSD Hybrid HD.
Next is the speaker. Full volume of the speaker will make the sound that came out of it "broken up" to the level that annoyed me so much.
The HD replacement was a breeze. The only thing that I hate the most is that, since the laptop was 4 years old (and getting older by the days) and most of the screws were tightened up so tight that I almost screw up with stripped screws (although I used the right tools). I lost myself with the time 'cause "operating" a MacBook was so much fun that I don't really care 'bout anything else except for being careful on every inch of the steps to ensure I didn't make any mistakes that would result in permanent damage of my beloved laptop. In the end, everything works just fine, not to mention the huge bump in the storage space.
The repair on the speaker was not that successful though. When I opened up the speaker part, the film on the speaker was damaged badly but still workable to some degree. And when I want to replace the speaker with the new one that I bought through ifixit (used and fully tested), I found out that the screw holders were broken (the newly bought speaker), so I can't hold the WiFi and bluetooth in place. I decided to keep the old speaker as it was (so that I will have sound) and live on with it. Massive bummer on the speaker repair.
Please make sure you read and follow the guides, or else you're crazy for trying something like "dissecting" delicate equipments without any proper instructions. Also, ensure you have a suitable working environment to work with (no kids, no pets, not on a carpet, and have a tray to keep all the screws organized as the screws are so small that if you lost them, you'll likely to lose them forever). Get a proper and sufficient lighting too.
On the cables, try to pry on the connectors and not the sockets or else, it'll be useless as the cables are very delicate and fragile.
Lastly, take it easy and don't rush.