Speaker began sounding very scratchy then quit working all together.
I purchased the overpriced $60 tool kit but was glad I had. It will come in handy for future small electronic repairs. Just wasn't happy about the price.
The instructions for the speaker replacement for the 4S from iFixit were very thorough. I had no problems at all. It took just under an hour from start to finish and was the first time I've worked on an iPhone. The repair was easier than I expected, though I am quite mechanically inclined. I wouldn't recommend attempting this repair if you tend to break things more when attempting repairs.
I used a large plastic cutting board as the work surface. The white background was great for those small parts.
The screws are tiny and several different sizes. I labeled ziplock bags with each size. The magnetic screw driver is a must.
The adhesives holding the battery and wifi antenna are keeping things in place very well. Take your time when prying these off. Don't expect them to come apart easily. I broke a pry tool when working the battery loose.
Would be very easy to over tighten the screws and strip something. Be careful with this during reassembly.