My MacBooPro5,3 was giving the dreaded 'Service Battery' warning. The battery itself was only lasting about 30-45 minutes on a full charge.
The repair was easy, just followed the guide. It really helped to have the specialized 5-Point Pentalobe screwdriver.
When removing the connector from the battery to the motherboard just take your time, don't force it. It will come off, the connection is just tight. I used a thin bladed micro screwdriver to assist.