Depends on your batch size, how fast you want to chill the wort, your water temp (well or city water?) and such...
IC's are ok, but you will get better results from either a CFC or plate chiller. I have a plate chiller (40 plate ChillHog 4000 from Rebel Brewer). I recirculate the wort through it (while chilling) for 5-8 minutes (back into the kettle) before running it to the fermenter. I got 7 gallons of boiling hot wort to 60F in about 15 minutes with my last batch.
I believe it took my brew buddy about 30 minutes to get to 65F with a 20' 3/8" OD IC using the exact same source water, on the same evening. He had about 5-5.5 gallons to chill.
I used an IC for several batches before moving over to the plate chiller. I can't imagine ever switching back. If anything, I would probably get a larger plate chiller once I go above 10 gallon batches (or ~12 gallons into fermenter).