With all the tempura I've eaten, I can really only count a handful of restaurants that do it really well. These days, I tend not to order tempura unless I can properly guess that it'll be done well, usually in higher end restaurants where they change the frying oil more often.
I've had two amazingly memorable experiences with tempura. One was well over 10 years ago in Japan at an ordinary tempura bar. I can still remember each course freshly fried as we ate and savored the lightly battered fishes and vegetables.
The second time was this most recent trip back to Tokyo. Again at a tempura bar - that seems to be the only way to go when you want tempura done the real way.
Tatsumi is the tempura bar in the Japanese restaurant in the Palace Hotel Tokyo. It is an exclusive six-seater bar. You definitely have to book ahead for a seat. The whole meal is like edible performance art. Watching the chef's artistry and craftsmanship while he plates the raw ingredients in preparation for the frying. You're pampered with leisure as you eat one dish at a time.
Lightly battered, piping hot, and crispy while showing off the fresh taste of the seasonal vegetables and fishes. This is another tempura bar meal for the books.
If you can't see the slide show here, check out my Flickr album: Tokyo Tempura