Comment by badsectoracula

IMO Gtk2 is better than Gtk1 as it did a significant number of improvements both in terms of features and usability. Later versions though aren't as great.

And TBH i do not think Gtk was ever "great", it was just fine and its main feature was availability because of the C API. For some time it was also the de-facto GUI API (during Gtk2 times) for Linux until Gtk3 broke that.