They were good back in the day, but, like always, a new SRB2 version makes me forget about previous versions.
Anyway, I remember the best update for me was when THZ2 and THZ3 were done. Looking at this version, it was a small update, but it was really nice back in the day, after just playing until THZ1.
Now I like more SRB2, previous versions were mostly really open spaces to run filled with crawlas and jetty-syns. Now there´s many more gameplay elements, enemies... It totally feels like a retail game. In fact, I wouldn´t mind paying for it.