I have not flown any ATR (not even as a passenger) but Dash 8-100, -300 and -400.
The Dash 8 is a very solid airplane with lots of backup systems. There is hardly any single malfunction that you'll find very uncomfortable to "live" with. Electric and hydraulic systems both have a lot of backups built in and the flight controls are doubled.
The -100 and -300 have decent performance and good short-field capabilities (we regularly flew to a 900m field in the Aegean sea).
Handling is OK, not very sprightly.
Given the age of the design FMS/TCAS/EGPWS integration on the -300 is not very good. We flew with UNS-1C which is a decent system (yet different from normal airline designs) but there isn't much map display except for your flight plan on the -300.
The whole flight deck isn't very modern and even the -400 has lots of switches and no "dark flight deck" as DeHavilland very faithfully kept the -300 layout to ensure a common typerating.
The -400 has lots of punch and power but the control feeling is worse due to additional springs and artificial "feel" elevator. When I flew the airplane you needed a very sensitive hand on the power levers as minimal movements would send you above/below glide on approach. (Apparently this has been somewhat corrected by changing the "throttle by wire" software.)
I fly a jet now as I had the opportunity to move up within the company, but still would give a thumbs-up to the Dash 8, especially if there is a perspective of the -400.