Based on a positive blurb in the Phoenix restaurant list and mentions here, I tried Niko's last night. In summary: relatively high prices for mediocre food. If it were cheaper, I'd rate it more kindly within it's own parameters, but $12 for dry, overcharred lamb souvalki with overcooked rice and too sweet tomato sauce is no fun. Did I hit it on a bad night? Anyone else been?
A few things were good: butter-grilled pita served with the appetizers was crisp and tasty. Taramosolata was mild and smooth. Skordalia was great, nice and garlicky with smooth potato. Tzatziki was good and super-garlicky but a little thick for my taste. Those three came on an ugly appetizer plate ringed with blah fried zucchini and eggplant.
Things went downhill from there. The spinach pie was bitter, heavy, and had little feta to perk it up. We tried moussaka (tasteless meat w/ heavy, unpleasant custard), pastitio (a step down from the moussaka w/ the same custard), meat dolamathes (not bad but a little salty), meatballs (salty and dry), salad (lackluster, tiny plates but that may be due to lettuce prices).
The waitress was nice and several Greek families were dining happily, but I've had better low-end Greek fare for less money (Greek Corner, Mass. Ave. Cambridge or some dishes at Andros Diner, Trapelo Rd., Belmont).