I've been trying out Oracle SQL-Developer 2.1 early adopter for the last couple of days, because SQL-Developer is the standard query tool at the company where I'm working.
Personally, I mostly use Aqua Data Studio. Apart from its odious activation scheme, ADS is excellent in every respect. However, ADS is kind of expensive, while SQL-Developer is free.
Previous versions of SQL-Developer were promising, but not very polished. They would paint strange colors on the screen in my installation, and behave poorly with regard to threading and large queries. The new version seems like a big improvement so far. Although it doesn't have the same brilliant keyboard support as ADS, it does seem to work pretty solidly, and appears reasonably attractive. (Much prettier than TOAD at any rate.)
I did notice one amusing glitch so far:
In fact the query only returned about 20 rows.