We just made our first batch of laundry detergent a week ago or so. Yes, we did have to grate and "cook" the soap to get it liquid. Took about 15 minutes total to do a 5 gallon buckets worth of soap!
At using 1/2 - 1 cup per load, this stuff is going to last a loooong time, so that 15 minutes was well worth it. (Average it to 3/4 cup per load and that's enough for approximately 107 loads per batch.) On a busy week, we do roughly 6-8 loads of laundry. Average that to 7 loads, and that one 5gal batch will last us about 15 weeks, or just about 4 months. For 15 minutes of work.
Now, with the soda and borax we have enough to make something like 6 - 5 gal batches, just need to buy more bars of soap. We ran a price comparison, and between the cost of Borax, washing soda, and the soap, for the number of loads we get, it costs a total of $12-$13. This is for 642 loads of laundry. The equivelent in commercial detergent would run around $85 - $90. Once it's all made, this should last approx. 91 weeks - close to 2 years!