Lincoln food isn't all that great! Basically, we have exactly the same food for first hall and formal hall (which is every night)....so.....our normal hall is 3courses and is way better than most normal halls at other colleges - it's not greasy fried food and is supposedly the healthiest of all the colleges. However, our formal hall is therefore very poor compared to most other colleges that put on special food for formal!
Regarding eating at other colleges, it's only possible if you have a friend who invites you or you get invited on a crew date. My little summary of halls I've been too:
Lincoln - like I said above. Normal hall good (guests can come), formal hall poor compared to others
Hertford - Good formal hall
Univ - Again good formal hall, although they say a grace at the end as well as beginning!
Queen's - I've only been to an MCR Guest Night, and the food was fairly good, but I didn't enjoy it as much as some others
BNC - Poor for formal hall. Very odd combination of food - breadcrumb coated chicken kiev with pasta!!! Again, has similar system to Lincoln I believe
New - Only ate their during interviews....food seemed generally quite fried. Can't comment on Formal hall
Mansfield - best formal hall I've been to (been twice and both occaisions lovely). Strange atmosphere though - small and quite bright hall, doesn't have same atmosphere as others, but food is very good!
I think that's the only colleges I've eaten at, but I may have lost count! lol