I suggest going here and reading the section "Steve's Conclusion":
http://www.steves-digicams.com/camera-reviews/fujifilm/finepix-s1500-zoom/fujifilm-finepix-1500-zoom-review.html
Based on reading his "Conclusion" I don't think the S1500 is going to be satisfactory for shooting in low-light conditions unless you use the flash. Pay careful attention to what he says about the lack of facial detail in low-light using the flash.
Like all digicams, the S1500 has a tiny sensor - 6.16mm x 4.62mm - stuffed with 10mp. Each individual pixel is miniscule and that means poor performance at ISO 400 and above. Compare that sensor to one in a DSLR and you'll find the average DSLR sensor measures 23.7mm x 15.7mm which is 13 times bigger. If the DSLR has 10mp you can easily see that the individual pixels are huge (13 times bigger) compared to the ones in the digicam sensor. Larger pixels means much better performance at higher ISO settings.
Since the S1500 does not allow the use of an external flash you're stuck with the pop-up flash and that's good for about 6 to 8 feet.
The lens on the S1500 is slow - f2.8 at the wide end and f5.0 at the telephoto end. In low-light, lens speed becomes critical since it allows you to use a lower ISO and that means better pictures.
With a DSLR, you have the ability to change lenses to suit the conditions. In a low-light situation you can change to a 50mm f1.4 lens and use a lower ISO. To get the same shutter speed at ISO 400 with an f1.4 lens you'd have to use ISO 1600 with the S1500 and your picture quality would be very poor.
If you are really serious about low light photography buy a DSLR.