Not neccesarily difficult but it limits you very much on what you can keep. Smaller size equals less fish or possibly only one fish depending on what you want. I started with a 20 and set-up a 10 as a QT tank for future additons. It turns out with my initial fish being a yellow tail damsel that my qt is pretty useless since there's really nothing fish wise I can put in my 20g with a damsel in there without risking some serious turf wars and possibly death of fish. So I've relegated myself to working with soft corals for now until my wife has said I pas the test and can get into something say in the 75g corner tank size.
A 10g isn't that tough but just restricting. ALso remember that at that size, when things start to go wrong, they go wrong very fast because of the size. In a larger tank you may catch small spikes in your water parameters earlier and be able to fix them easier than in the smaller tank size. I'm a newbie so I hope I havent confused you.