Celtic Cross comes across as a fairly normal DM level. There are some weird bits, such as a plasma gun tucked into a dead-end corner all by itself, and some cool bits including a lower pit area that looks quite nice.
The theme doesn't seem very Celtic, everything is bathed in blue ad nauseam - even the blue doors that belong in CTF maps feature here. Bots occasionally jump into deathfog but otherwise perform well.
Games can be fun with battles for the railgun and rocketlauncher a focus. That said, the RL is right beneath the RG; its a bit easy to grab both.
Average DM level that's worth checking out if you're not too picky.
-Reviewed by Octovus