This is my first roaster, but I have been relentlessly roasting with it for seven months now and have had no significant problems. Other reviews of this machine indicate that there may be quality control problems in its manufacture. However, I've had no real problems and may have simply lucked out in avoiding a lemon.
The first caveat is voltage. When this machine was initially run on my house voltage, it did indeed have the problem mentioned elsewhere of overextended roast times. After my wife banished me and my coffeesmoke generator to my professional woodworking shop, the problem happily went away. My shop voltage is more up to snuff. Users experiencing lackadaisical heating might be advised to buy a voltage transforming "Variac" reviewed elsewhere on this site.
There are some tricks you can play with the Rosto to get the best out of it. The noise level is too high to distinctly hear the second crack, but this is easily remedied by just briefly turning the machine off for a few seconds to listen to the crack. I may toggle the machine on and off a few times as the second crack approaches so that I can hear just exactly what's going on. Such practice probably violates the warranty, but it doesn't seem to have harmed my roaster. The too hot cool down cycle is gotten around by prying the roaster lid off with a butter knife taking care to also trap the now heat loosened silicone sealing ring with the knife so that it comes away with the lid all of a piece and doesn't fall into the swirling roasting chamber. With the timer dial turned to cool and the lid removed the cooldown is quite fast. As you may have guessed, I don't pay any attention to the machine's timer. There are too many day to day ambient variables that render the time clock approach unreliable. I just crank the timer all the way over to maximum and play it by sight, smell and sound: then crank it over to cooldown position and pop the lid when the roast is ready to terminate. Many Rosto users do just fine working out repeatable timing schemes for their favorite beans, but I've noticed that some of them use their own separate timers - not the Rosto's. Since I am often experimenting with different beans and different "melanges" of roast blends, I just find it easier and more interesting to "wing it."
Dry-processed beans like my favorite Yemeni will create so much chaff that it can pack the collector basket and so restrict airflow that the lower levels of chaff can actually catch fire. It happened to me...once. With real chaffy beans you can pry the lid off slightly at about midroast and mid-chaff level in the basket, rotate the lid 90 degrees to reveal the chaff basket, then pull the basket out with a pair of needlenose pliers, dump it, and then put it back in and rotate the lid back to fully closed all without seeming to interfere adversely with the roast. Of course, the lid is very hot, so you have to mind your fingers, and you will be sprinkled with blowing coffee chaff; but I prefer to think of it as coffee confetti in celebration of another fine batch of fresh roasted beans. With washed beans or just naturally low chaff beans none of this is necessary.
The Rosto manual says to wait fifteeen minutes between roasts to allow for adequate cooldown of the machine, but if you are in a hurry to do several sequential roasts you can dump your beans and then crank the timer back up to the beginning of cooldown and let it run back down again. This cools it off in about five minutes. I have always used the full cup measure of beans rather than the 7/8 measure advocated by some other Rosto users. Roasts still seem to be even no matter the bean - big, small, dense, or light. It does help to use the "Rockin' Rosto" technique whereby you tilt the machine back and forth as it is roasting so as to mix things up and avoid heat stratification.
Well, this all sounds a bit complicated; but do it once and you don't even think about it after that. All in all, this is my kind of machine. You can fiddle with it and make it your own, and if you can get a good one - as mine seems to be- it may turn out to be a very good one - robust and reliable.
As for the quality of roast- the roast profile seems to be good. Light city to espresso - all are achievable with none of the gassy or baked flavor that can be a problem with air roasters. My fellow coffee geeks like the cups I serve them from this machine's output. If you are new to home roasting, it needs to be strongly reiterated here that fresh roasted beans need at least twelve hours and, in some cases, two days to fully degas and develop flavor. Beans right out of the roaster have a very lame taste.