There is plenty of information on this if you do some searches, but in one word.. Reload.  They have the best reload sailors in the game and also have some great lower tier BBs with lots of R slot guns that are fun to play.  

In a WaW room their R slot guns can be like AA gus from other nations for high level uncapped sailors. Their BB's have no decent AA gun but you can load up PHH or HH on all those T slots and pound away at subs with lower level BBs.  

Just keep reading for more info.  I found the RM line to be tons of fun working my way to BB6.  There really is not a bad BB in the line if you ask me.

Enjoy the Game. 

I know there are other topics on this as well but. How is the bb5? Some advantages/disadvantages

Well I did level the RM line before the nerf of the VV.  Actually I should say at the time of the VV nerf I had just leveled to RM BB6.   I played more of a rush and shot style with RM VV with the (formerly) 30 gun and fast reload as long as you hit your first salvo on the way in you could pretty much take out anything with the faster reload.  AW were harder due to low angle guns but you could always use AP. 

The comments in the link probably reflect a better stratagy for VV post nerf except I always would take advantage of HH with all those T stlots.  I leveled and extra pair of reps to use on T slots when here is a low sub envirement to keep options open.

Still the RM line BBs have  lot to offer the BB1 is an excelent sub hunter, the Caio Duilio is murder if you get with in range with 13 barrels of fun.  Be sure to raise BOs for both lines you wont regret it.

Enjoy the Game.

 

Excellent top-tier sub.

Very good Fighters and Torp Bombers.

Pizza night on the mess deck.

Italy's best advantage is its premier status for leveling new sailors. Once you have a crew, Italian DD/CL/CA can run the 6" and 10" EOC guns, zip into a GB and score a few hits, and come out with experience that would make blitz kings cry. And they can to it at every level from 12 to 60. Then they get a beastly BB2 to finish.