From what I understand, there haven't been serious issues with the machines. One recycling plant mentioned in the Worksaver magazine claimed to have run an A220 ("predecessor" in some ways to the A300) for 5,000 hours without a major malfunction, all the while without using perfect maintenance. The goal was to see if the axles would hold up. On the other hand, this is a Bobcat article and I don't know how much of the "little errors) they may have left out.
At any rate, I think the A300 is one of the best machines out there for finished surfaces (as 2004F550 mentioned). I think the machine is still too expensive to justify as a skid steer (eg, why buy A300 when you could have an S300 for thousands less), but as a complement, used in the same way as a CTL is a complement, the A300 could be a bigger money maker for some. I guess we'll see how well it goes in a few years... if Bobcat ditches the concept, it didn't perform.