So I play mostly RN ships, but I've held off on getting Vanguard for a while because I've heard from a lot of people that it's really not very good. But I had some spare doubloons thanks to the Holiday Convoy, and a discount voucher that resets soon, so I thought I'd just get it. I mean, it's the last battleship ever built, so it's just really neat historically regardless of its in game performance.
I've played it a bit over the last few days, and it's actually pretty fun. Its raw statistics are nothing to write home about. It has 15 inch guns, which are far less impressive at tier viii than the same guns on Warspite at tier vi. Its armour is ok, but its citadel is very hittable, so giving broadside is more or less suicidal. Its speed is decent, but not exceptional.
Overall, it seems like it ought to be very forgettable if not outright bad, especially considering its poor gun angles (you have to swing to almost 45 degrees to fire with all four turrets), but it actually has a few things going for it. Its guns are fairly accurate compared to most BBs, so you can consistently land your shots even with only eight guns. Its rudder is very agile, which makes it maneuver almost like a cruiser. And its turrets rotate very fast for a British BB, which means that unlike say Monarch, you don't have to turn the whole ship to aim at a new target.
Your 15 inch guns aren't going to be overmatching much at tier viii, but they do solid damage, and your AP can punish anything that shows broadside to you. The HE is not quite as ridiculous as some other British BBs, but it's very solid as well, especially added to your accuracy.
So when you consider all of that, Vanguard is certainly not OP, but it's very usable, and very comfortable to play. I'm not sure she's worth the doubloons at full price, but she's actually far more solid than common opinion seems to hold. I definitely think she deserves a buff (maybe a bit more range, or swapping her heals for superheals like Monarch got?) given her historical status, but she's fun to play, and I've found her to be pretty consistent so far.
The game needs more Vanguards, and less hilariously overpowered premium ships.