I've only had the putter for two rounds, but so far, so good. The heavy, stainless steel putter head looks indestructible.
It does what it says it will do: it stabilizes your stroke, making it much more difficult to push or pull those pesky three footers. Some say it's harder to get feel on long putts... I disagree. The Heavy Putter basically makes reading the green your only worry. Some also say the ball-and-a-half alignment aid is distracting... again, I find it simple and effective. I usually take about 36-38 putts per round. Today, I finished with 29 putts, a career low.
While it probably won't break your back to carry around, it does add a bit of noticeable weight to your bag. Also, the Heavy Putters come with interchangeable weights that increase or decrease the weight slightly, but when your putter already weighs 900 total grams between the putter head and the added weights under the grip, I find the effect is negligible.
Newer models of Heavy Putters can run from $169-$199 retail, but if you struggle with a wristy putting stroke, it's well worth it. But you have to trust it: don't expect it to work if you flick at the ball with the putter. The Heavy Putters train you to develop a pure pendulum stroke, one that keeps the ball consistently on-line.