I have been really lucky using Ralph Lauren paints. I have used the latex paints, the crackle medium, the duchess satin and River Rock.
River Rock I used the sand colour River Rock in my kitchen! I did not have any problem with the application at al and I did not use the special roller, and I rolled it on exactly as I would any paint. The only thing I did, which I can't rememer if it was suggested or not, was I painted with a cheap flat latex as close to the River Rock colour as possible fist. This seemed a sensible idea to me. Years ago I used those spray cans of stone paint and I found at that time it worked much better, and the stone paint went farther if I did this...so, when I got the River Rock I just did the same thing. The results I got were so good and was so easy for me that other friends of mine have used the paint also.
Two of my friends used one of the greys and they had problems getting an even application. I thought at first that this was just due to their relative inexperience with painting until I noticed that even dispaly rooms at IKEA that seem to have used the River Rock also seem to have streaking problems. I assume that IKEA hires expereiences painters. I don't think either of my friends painted a matching base coat first, maybe this does make a difference. I have also found the River Rock paint to be extremely durable, as I mentioned I used it in my kitchen, and I have scrubbed the walls pretty thoroughly with no dtriment to the paint finish.
Crackle Finish I used the crackle medium for my kitchen cabinets. I couldn't seem to get the sponge method to work very well to create a porcelain finish but I used a sponge brush and stroked on the top coat with a varied angle to the strokes and got an interesting crackle effect. I did two different types of paint for the top coat. I found a flat paint had such a fast drying time that it was very unforgiving and you really couldn't go over any area twice (which the can warns you of). For some surfaces I used a gloss paint (which went against the can recommendations). I found that the gloss paint gave me such a long drying time that I had no problem when I went over an area more than once, as long as the crackle process has not begun.
Latex I have used the latex paints as a normal paint and to faux finish paint my livingroom. I used a burgundy and a dark green in this room. Any shade of red paint is the hardest paint to cover with. It is often recommended to first paint with a red tinted primmer first to achieve a better coverage. I believe RL also makes this suggestion. I have been happy with the results I received with the latex in my livingroom.
Duchess Satin I have only used this paint to do a faux finish in my bedroom and have painted a small bed side table. In both cases it went on like and other latex and gives a nice finish.
All in all I have been happy with the results I have gotten with RL paints, but I do give people a warning that I seem to have been in a very small minority of people who have had as good of results with the River Rock.