I had a 310I and 340A once...didn't own them, but they were pretty much mine within the company to use, and I flew them quite a bit. I thought the 310 was great. It has great single engine service ceiling, good speed and performance for it's power, it's economical to fly, the systems are very simple and straight forward, and you wouldn't believe what I could haul around in one. (really).
I operated it in all kinds of weather, and it was just terriffic. I didn't care for the entrance door; it's a flimsy thing that doesn't fit particularly well, like many similiar doors on light singles and twins.
It's an easy airplane to work on, and an easy airplane to fly. I used it for training as well, and did some new hire screening in it occasionaly, as well as training for low level contact work. It did just fine.
Some folks will put down the landing gear...more than a few have folded them. In many cases, it's purely pilot error, often a taxi issue with damage to the nosegear.
I never noticed any of the instabiity that some folks here have mentioned. To each his own, I guess. I've flown some truly unstable airplanes, and this wasn't even close.
I don't understand some of the complaints about Senecas...I flew II's and III's for several hundred hours, and thought they did just fine. I used them in and out of some fairly rough fields in rough conditions, and never had a lick of trouble. Decent single engine performance, decent speed, not a bad airplane, excepting some of the gear maintenance issues.
Running an airplane out of fuel is in most all cases, an act of darwinism, and is only proof of lack of forethought.