EA Ermor: 3 4 3 2 3 (Solid yet unspectacular early game with legionaries, nice communion battlemagic potential in mid game. Low max levels in S prevent it from being the late game powerhouse other S nations can be. Mastering communions and lots of low-level not easy to boost paths make it quite tricky to learn. )
EA Sauromatia 4 4 4 3 3 (Just plain solid nation, with a large variety of strong options in all stages of the game. It might be worth a 2 in ease of learning simply due to the large number of options available, but in the end went with 3 as whatever option you choose is bound to be at least decent. )
EA Helheim: 5 3 3 4 4 (Obvious early game power. They do have a good number of mid/late game options available (magma eruption, good A/D magic, powerful(flying) stealthy raiders, but a lot of it is capital only, lowering their rating a bit. )
EA Yomi: 1 4 3 2 2 (Easily the most difficult expansion of all nations I played so far. Mid game with recruitable Dai Oni and strong battlemagic is very solid. Mastering early expansion, figuring the best uses for the quite crappy military, and the many uses of Dai Oni make them quite hard to learn. )
EA Oceania: 5 1 2 3 3 (Amazing early game potential, but getting out of the water is an unbelievable pain in the ***. Their only saving grace past early game is easy clam-access. )
MA Ulm: 2 4 2 4 4 (Your troops are decent enough for expansion, but you have a number of vulnerablilities in early wars. Hordes of smiths spamming magma eruption behind a wall of steel make mid-game their day of glory. Late game their lack of magic diversity haunts them. The limited number of magic paths make them quite easy to use and script. )
MA Abysia: 3 4 3 2 2 (Solid and fire immune if expensive troops and fire evocations make for a decent enough early and mid game. Late game they can leverage the power of blood, but expensive & capital only bloodhunters and lack of other tricks limits them. Crippling capital dependance, old age issues, blood magic, and path boosting difficulties make this nation hard to play.
MA C'tis: 2 4 3 2 2 (Recruitable everywhere marshmasters with skellespam and poison tricks make for a very powerful mid game. Late game marshmasters remain top-class mages, and shaman/couatls allow communions and astral tricks. The miasma makes it difficult to diversify their magic though (bringing their lategame rating down a notch) and also explains the low learning/ease of use ratings. )
MA Jotunheim: 4 4 3 4 3 (Easily massable sacreds for a potentially strong early game, cheap researchers, thugs and body ethereal in mid game. Somehow, despite having astral, death and blood magic I feel they slowly peter out towards late game. )
MA R'lyeh: 3 3 5 2 3 (Nothing extraordinary about the early stages of their game, but nigh on unstopable as soon as you get your Starspawn & cheap communion slaves going. Learing how to get out of the water with chaffy troops and communions make them not the easiest nation to learn. )
LA Pangaea: 4 3 3 4 4 (Two very different but equally nice varieties of sacreds and minotaurs make early game a breeze. Mid game your Pans can buff your very solid military to greater hights. High hp mages and troops and high MR are great assets for late game, but you lack magical diversity. )
LA Utgard: 4 4 4 2 3 (A very solid nation all around. Good sacreds, strong thugs, amazing cheap mages, strong communions, very decent S/D magic, and good blood access.
LA Atlantis: 2 3 2 4 5 (Strong but resource heavy troops. Coupled with strong W/D mages and cold resistant troops they make for a decent mid game. Late game the mages high hp and high death magic are useful, but appalling lack of other options leave them rather weak. That same lack of options and obvious strengths make them easy to use though. )
LA R'lyeh: 4 4 5 2 1 (I agree with QM about giving LA R'lyeh a 6 for endgame strength.
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Masses of freespawn chaff make for good expansion, and proper use of illithids and mages make early/mid game solid enough. Late game is ridiculously powerful, combining MA's magical power with virtually limitless chaff hordes - who suddenly become a lot more fearsome when massively buffed by your communions. Freespawn requiring two kinds of leadership, madness and large communions makes playing them a micromanagement nightmare. )