Some are prety good but get a good replacement warranty.

Rarely do a set have equal brightness.
And even the good ones can start to fail quickly.
And styles change so fast you might not be able to match the others in the set.

Low voltage is still the better way to go IMO. Cheap safe and they work. Some of the better systems are really bright.

The newer multiple LED solars work quite well. Metal construction is preferable to plastic, but even with the cheapo solar accent lighting, our extensive experience has been very good over the last three years with various brands (Malibu, Sunergy, Westinghouse, Galaxy).

Here's a link to a discussion a while back on the Landscaping Forum where I contributed two posts (jkom51), near the end. Note my points on siting them however -- if you don't have the right site for them, you're wasting your money.