I do like RunKeeper a lot. I really like being able to see the splits at the end of a run. I have noticed the pace measurements are a little laggy - but, being a newer runner, I try not to put too much emphasis on pace during a run. I'm more interested in my average pace overall for each run.
As for accuracy, I do realize that different devices will have slight variations in distance, therefore affecting pace. My concern really was the huge amount of variation within C25K app itself. The pace and distance in the 'free run' sessions were wildly different than in the workout sessions, on more than one occassion. I can't figure how that was possible more than once. But I'm glad I realized it sooner rather than later. It led me to find better tools for the job.