I'm a filthy Rammus player myself and IIRC he was actually hit with a really hard nerf not long ago, where:
-
They made his Q a channeled ability, reduced it's duration, reduced it's base damage, reduced the slow duration and reduced it's radius (although this can also be seen as a buff as it made it easier to navigate around minions).
-
Made his W self-slow him.
-
Removed his armor reduction on his E.
-
Reduced the base damage on his ultimate and reduced his AP scaling.
They also nerfed him when they reworked Thornmail as it reduced the total armor on the item, reduced it's damage and it now slows the enemies' auto attacks so he can't get as many reflects back at the champion attacking him.
There's also tons of counterplay towards him:
-
If you hit him cc, it will stop his Q as it is a channeled ability, effectively making him useless as his Q is his only gap-closer in his kit.
-
If you hide behind a minion wave, he is either forced to go all the way around it, or collide with it which makes him useless once again since it is his only gap-closer.
-
Since he needs to build a lot of armor in order to survive the ADCS he is inevitably forced to taunt, you can build armor penetration items such as Last Whisper or Black Cleaver.
-
Since he is also forced to build a lot of armor in order to deal any meaningful damage, he is very vulnerable to champion who deal magic damage such as mages or casters. Ganking mid lane is one of the worst experiences for a Rammus player.
-
You can build QSS to instantly free yourself from his taunt.
-
Since his Q doesn't give movement speed immediately and it has to ramp up over time, I find it hard to believe that you are so easily ganked by him even when you have your bushes warded.
Overall I'd say Rammus is one of the most balanced champions right now. I actually think he needs a buff to be honest but I may be biased since I play him. I really looked forward to the runes Riot showcased in a screenshot that would reduce damage taken and then reflect it back to the person attacking you. I was so excited for them and thought it was finally my time to shine as Rammus but then I checked the preseason update page and I was severely dissapointed.
The runes I was looking forward to were showcased in this video at 0:25
Click here to see the preseason update page. I highly recommend you do, so you can theory craft runes builds and be prepared for when the patch hits.