As it happens I was able to buy a Ricoh GR with a coupon back in December. It wasn't quite 400 bucks, but it was close so I went for it. I've been using two different S90s exclusively since 2009, and felt like I had gotten pretty close to that cameras limits. Having wanted a little more for a while, a trip to New Zealand in January and a kid coming this summer seemed like a good excuse to buy something.
I like taking pictures, but don't put a ton of time and effort into it. I tend to run and gun throughout the day and rarely stop for more than a minute to shoot.
Overall I like the GR. The controls are very well thought out. I can do pretty much any mode changes I want with gloves on, which hasn't been the case since I gave up my FM2n. The camera powers up super fast for a digital, and the burst mode works very well. The routine useability of the GR is a massive improvement over the S90.
I find the autofocus on the GR underwhelming. Detailed reading of the manual reveals what the various settings do, and with practice I've been able to mostly get it to do what I want, but I'd still characterize the close focus/macro ability as just plain poor. This remains a big disappointment given the cost.
Image quality is better than the S90, and I'd spitball it as on par or better than my wife's RX100 mark1. It prints tack sharp. I still lust after a DP2M, but it's probable that my skill and lack of dedication are holding the GR back. Video quality and sound are also very good.
I haven't had durability issues with the plastic body, but I do worry about it. The light weight is nice, but if given a vote I'd pick a metal body instead. I also dislike the large hollow around the lens when it's open and deployed. It functions as a huge catch for rain drops and snowflakes and I worry about the longterm impact on the cameras life.
Overall I'm happy with the GR. It's far from perfect but has been a worthy investment.