FYI: the 212 plus has been replaced by the 212 evo, a few small differences, but get the evo if you can as it comes with a free second fan clip which when used with a compatable fan decrease temperatures by a further 3-4 degC.
The Intel coolers aren't bad, but having an aftermarket cooler means it will run cooler, meaning less noise, less heat, a better looking fan in your case (if that's your thing) and much better overclocking headroom. all for the price of sacrificing a few takeaway coffees (40 bucks!)
I know that the new IB are suppose to get a bit hotter than the SB.
I plan on researching and doing a small to moderate O/C when my build is completed.
Should I get an aftermarket cooler if I have this setup?
You have 2 primary decisions to make as follows:
If you want to leave your CPU at stock or close to stock levels, you can keep the intel HSF and usually run no more then 70-75 degrees on a prime95 blend test. Of course, this depends strongly on your voltage (My mobo happened to use 1.24v as auto voltage @ 3.7Ghz which sucks! Needless to say I use manual voltage now for my stock levels, 1.120v and running 10-15 degrees cooler)
If you plan on overclocking, even by say 500+Mhz, then you will 100% need some type of aftermarket cooling to keep your temps down. If you want to do an extreme overclock like 4.6++Ghz, you will want something that can hold its own against your cpu temps.
That being said, the Hyper 212 Evo is definitely a good starter, say if you want to OC to about 4.5Ghz.. perhaps more or less depending on your CPU, Mobo, Vcore, etc etc.
If you want to go even further then that, you may want to consider a higher performing HSF, starting with something like a Havik 140 by NZXT, the ever popular (known to be pretty much top of the line air cooler) Noctua NH D14, or you can even start getting in to closed loop liquid cooling (Corsairs H60, H70, H80, H100)(Antec Kuhler 920 or 620)
You should consider what you will be doing with your CPU and decide if OCing is for you, if it is, a good HSF will be your best friend.