I don't think R'lyeh is easy for beginners in general.
Most of your troops either have the protection value of a newborn kitten or are painfully s...l....o...w. The Void Gate which summons your Sacred troops is, well...IÄ IÄ FTAGHN! *rips off his clothes and runs around wildly while being hunted by a Horror*, errr, funky. Yes, it's quite funky.
Then you have trick units like the Crab Hybrids, Shambler Thralls and the Illithids. Illithids are very good, excelent in fact.
You have an S1 mage who is also an assasin, S1 and 100%WSED priest mage who is the ony who can use the void gate, um, semi-reliably and the crown jewel of your mages the 3S 1W 100%WSED (or was it two randoms? I forgot!) Starspawn. So you won't have much evocations. Instead you have to rely largely on Astral magic and perhaps stuff like Gifts from Heaven and Nether Darts for combat.
That's what I think. Perhaps some newbies find them easy to use but I'd vager they have hard, frustarting time trying to invade the land with the low-prot units who will get easily killed by archers.
But they do have a solution for that, oh yes they do...