Arezzo worth a visit?

It's a nice little city with lots of history (it's older than Florence in fact). It will make a great day trip.

http://en.m.wikipedia.org/wiki/Arezzo
http://www.visitarezzo.com/what-see-arezzo-amphitheatre-piazza-grande-vasari-petrarca-house-fortress-medici-turism

A fellow guide did recommend it to me, but I ran out of time.

Beautiful small city, main piazza has some good restaurant choices. One day two friends and I watched a nonna (grandmother) making tortellini for the family restaurant. Some interesting churches and a castle at the top of the city.

And don't forget gold jewelry. Arezzo is the gold jewelry capital of Italy.

Since I'm a Florentine of Aretino origin (both my parents came from the area) here are some language courses:
English-Italian-ARETINO
Boy-Ragazzo-CITTO (the C is pronounced like the soft C in Church)
Girl-Ragazza-CITTA (note that the final A is without accent, otherwise it means city)
Baby-Bambino-CITTINO (CITTINA for baby girl)
Come on!-Forza! (or 'Dai!') - ALO' (Aretinos say ALO' every sentence, so it's the most important word to know)

Now you are ready to go to Arezzo. Don't miss it! Alo'.

does Arezzo have a ZTL?

Yes, ZTL in Arezzo. I don't remember exactly where my friend parked, but it was a short walk to the historic center.

I found a Italian website that shows all the ZTLs and parking in Tuscany and it appears up to date:
http://www.accessibilitacentristorici.it/ztl/toscana/lucca.html

An Aretine friend and I discovered the hard way last weekend that you now need advance reservations to see Piero della Francesca's fresco cycle The Legend of the True Cross. We showed up on a Saturday afternoon and the next opening wasn't until late Sunday.

Yes there is a ZTL in Arezzo. One large parking lot is along the City Walls, on Via Giuseppe Petri, then you can take escalators up to the top next to the cathedral (the tourist info office is also at the top of the escalator).