Well, the Troy Built tillers of today aren't built as good as the ones built some 20 years ago but they are typically better than many of the other ones out there. MTD has taken over building a large portion of the yard and tiller equipment anymore and they tend to make stuff a little on the cheap side.
The nice thing about Troy Builts is that they are normally gear driven instead of belt driven and they normally have more durable gearing than some of the other brands in the transmission.
The reverse rotating tines tend to break up the ground better more, but it is easier to get your tiller stuck and you'll tend to have dirt build up under your tiller more. Forward rotating tines will tend to help push or pull your tiller through the ground better but they won't chop the dirt up as finely as the counter-rotating tines will. I prefer to use the forward rotating tines to initially break up the dirt, then come back and use counter-rotating tines on the second time through to bust the dirt up into a powder.
If you have a half acre garden, I recommend getting a good quality tiller that is driven by gears instead of a belt. It will definitely be worth it in the long run.
I've heard of another brand that is supposed to be better than Troy Built now. The color of the tiller is blue. But I can't remember the name of the tiller brand.
Also try avoiding a tiller that has a Tecumseh engine on it. The Tecumseh engines don't work very well.
Briggs & Stratton engines are OK. Kohler and Honda engines are good.
If you have a descent size garden tractor that has a PTO, you might consider getting a PTO tiller that fits onto the back of your garden tractor, then just using a pretty small tiller for weeding. A PTO driven tiller will till your garde in half the time or less and will till deeper than a regular garden tiller.