I bought my 3340 in 2005 with about 750 hours on it. The main use for it is to hay about 30 acres two or three times a year. It's also used to feed out hay almost every day during the winter. For me, this tractor is exactly what I want:
First, it was inexpensive ($12.5K), and second it's heavy so the haying implements don't push it around. I upped the hp from 48 to about 60 and it handles all implements just fine. Reliability is only average. I've had to replace both master and slave hydraulic clutch cylinders. Not a problem if you are handy since my nearest dealer is 100 miles away.
Oh, there's a great web site (zetorworld.com) where I get lot's of help on Zetor specific issues. Overall, I like my tractor.