It's not terribly difficult, but most guides I've found have had you tearing the whole thing apart, which is entirely unnecessary.
If you get an LCD&Digitizer combo part, all you have to do is pop off the back cover and the midframe. You can do this with a guitar pick, fingernail, or iSesamo. Once you have both off, pop off the battery connector (You'll know it by 6 wires attached to a white connector. Use a plastic spudger's tip to pop it off, just be careful.), and completely remove the cable that connects the LCD to the motherboard. It's to the right of the Battery Connection. Remove the cable, and you should be good to take up the screen. Go slow, use a lot of heat and an iSesamo (I use a hair dryer, perfect heat with no risk of damage).
Be very mindful of the top and bottom of the device (The top has a camera and a sensor, be very careful with taking up adhesive here. The bottom has the home button assembly, be very mindful of that, you could cut the cable. Soft keys should be on your replacement part.). Clear off old adhesive on the frame, lay tape down (I personally use TESA tape, works great and no glue needed.) At this point you can put everything back together. just make sure to keep the tape on the circuit board of the new part on. It's to prevent it from grounding out.
Hope this helps. Oh and be careful, too, I guess. Haha.