I feel reasonably well informed having spent 3 1/2 years 18 from the bottom of the co pilots list! Only just started moving up and rosters are good.
Its been fine, very rarely get blind lines, work most weekends, but i'm prepared to do that to get decent trips. Blind lines are great for a tactical weekend but to be honest if you're very junior you'll only get the rubbish blind lines (NRT, LAX etc) so you're better off taking a trip line. Multiple weekends off in a month is a problem, but not insurmountable. Lots of people swap trips regularly and you'll be surprised what pops up there. Weekend trips are often more fun (junior captains and fos more to do downroute etc). Theres much less stratification of trips on the FOs rosters than the Capts as majority of good trips have 2 fos but 1 capt. For example every night BA have 24 fos at some point on a HKG trip but only 16 on JFKs.
Most of the trips are fine, I think we're a bit spoilt compared to the junior 777 boys. Looking back over the last few years i've averaged 1 2man trip each month (JFK most often) 2 3 man (generally a 4 day and a 3 day) and 1 4man (HKG or GRU usually, SIN is senior), but in last 6 months i've only done 2 x 2 crew and more 4 crew than 3. Average 13 days off, 10 would be an extremely busy month and you'd be putting lots of hours in the bank if you were bidding well.
However if you do need weekends you will a, spend your life on the E coast and b, work on average 1-2 days more per month due the lack of hours these trips accrue.
Roster stability wise, you almost never get disrupted, but you'll have to do 1 standby month per year. However this is an excellent chance to pick up some great trips at the second stage of bidding so is not all bad.
pm me if you want more info.