I lived in Walsh all 4 years I was at ND and I loved it. I liked the fact that it was so old- it's a beautiful building with a lot of charm and character. I also like that it's a pretty small dorm, so you feel like you know a lot of the people who live there. There is an elevator- it's old and slow, so no one uses it on a regular basis, but it helps a lot with move-in and laundry! There is a lot of 24 hour space also-half the basement (including 2 TV rooms)-which is more than a lot of the dorms have. And the kitchen, laundry, and workout room in the basement are all pretty good. Living on God Quad is great too! You are in between North and South Quad so both dining halls and all the classroom buildings are easily accessible and it's super close to LaFun. God Quad is also probably the prettiest place on campus, but rooms on both sides of the dorm have good views (God Quad/the dome or Bond Quad/the lakes). Walsh also has great bay windows in a lot of the rooms, a lot of single rooms, and some rooms with private bathrooms.
As far as cons, you do get the occasional cockroach (I saw 3 in 4 years, so not a lot, but a bit of a shock since I'd never seen them in MN!) and we even had a bat in the attic once. There is also no AC, but there were maybe 3 nights in 4 years that that was an issue for me. It really doesn't get that hot during the school year, though I would recommend bringing a fan. Rooms are smaller than some others on campus, but with the newer dorms on campus, they are turning a lot of the smaller doubles into singles and quints into quads, so that has relieved a lot of the congestion. Also, if you order Chinese delivery, they will usually get confused and bring it to Welsh Fam, no matter how many times you clarify that it's "Walsh with an A!"
Let me know if you have any other questions!