www.steves-digicams.com has done full reviews of both the S5is and G9 in the last 3 months. Both outstanding in their categories.
G9... 12 Mp, 6X, and more.... more of a pocketable camera
S5... 8 Mp, 12X, and more.... More like a small fixed lens SLR type body.
My favorite review sites... Steves (above),
www.dpreview.com,
www.dcresource.com.
Dpreview has camera or brand specific forums as mentioned before. Steves has forums. Don't know about forums on DCresource...mostly just read their reviews for another angle.
Also search Yahoo or Google for user forums. Cameras as popular as the S5 often have user groups/forums.
I am giving lessons to a lady right now on an S3 is, and it's a MAJOR WADE through the manual. The camera can be easily used by any proficient photographer for manual control, but the custom features and settings that can be used to create user profiles are way, way overkill. It took me less time to master a PC than it would one of these high end consumer level cameras, and I've been shooting film for 40 years and digital for 7-8.
While the G9 is 12 Mp and the S5 is 8, remember that the sensor is small. The sensors in these cameras are small by comparison to a DSLR, and miniscule related to the 35mm full frame film. They keep improving the processors and dragging more Megapixels out of these cameras, but I am suspect on 12 Mp out of a sensor that just a couple of years ago topped out at 7-8Mp.
Here is a link to an interesting page on sensor sizes at Dpreview:
http://www.dpreview.com/learn/?/key=sensor+sizes
The S5 has a 1/2.5" sensor and the G9 has a 1/1.7" sensor. Regardless of how that looks in numbers, the G9 sensor is bigger, explaining the 12Mp yield. However, both of those sensors are a fraction of the size of a DSLR at 8 or 12 Mp.
All that technical stuff aside, If you father wants a great camera that will yield high quality prints up to 8X10 or 11X14, either of those cameras would be good choices, based on the reviews.
Two important things I put at the top of the list are:
If you are going to be shooting family events, or any sports activities... Shutter Lag
If you are going to be shooting low light, at ISO does the noise become unusable in printing.
All the other things pretty much fall into place with name brand cameras. Noise is an ongoing issue for small sensors. Shutter lag can make a camera unusable for spontaneous shooting where movement is unpredictable.