Compact digitals at their simplest will have "program" shooting only. I.e. you get to choose where the lens is pointing anf when to press the shutter release and that is about your lot. Some will give you alternate programs that bias the results toward either smaller appature for greater depth of field, or faster shutter for better sharpness of moving subjects. A few give you partial or even full manual control (i.e. the shutter or aperture priority of old, with a few bells and whistles). To be fair though I have full manual control on my old SLR and hardly ever use it, since it moving flashing LEDs up and down never "feels" the same as it did with the old alnalogue camera metering systems where you adjusted things until a needle crossed a circle! ;-)
The main thing you loose is several f stops. So you get less light gathering capability that with a bigger lens. So you may find that with an adaption lens on you only get f5 at the widest setting. That can curtail your options in poor light. The smaller lens will probobly not resove the fine detail you could expect from a bigger SLR lens, and you don't get the option of fitting a prime lens (i.e. all compatcs will have some form of zoom lens) on the occations where the extra definition or better light capturing capability matters. (A film based SLR Nikon will often have a 50mm lens that opens up to f1.2 which is seriously bright and fast)
(Brother in Law is the editor!)