Fenixes I've owned:
L1P: the original model that got it all started. This light was great, it fulfilled the functions of my older and clunkier 123-powered luxeon lights while running on a single NiMH AA cell, near-zero-cost operation in a trim form factor with no silly "tactical' pretentions. it was my main light for an overseas trip last summer to a place with unreliable electricity and no streetlamps. I just made sure to keep a few cells charged up for it. But i felt it became obsolete with the introduction of the Cree XR-E led. A friend of mine admired it and hinted that she'd like one to use at work, so I gave it to her.
L0D CE: got this while I still had the L1p, and comparison found they were equally bright even though the L0D CE was using half the power. That made it easier to give away the L1P since the L0D's smaller size makes it much easier to drop in a pocket. I found its computerized interface to be a minor nuisance but despite this it was still a frequent EDC until just now (see below).
P1CE: single level 123 light, very bright with lots of throw because of its larger reflector. The best-made Fenix that I've had so far. Basically a copy of the famous LL123 in my opinion. I don't use it much since for EDC purposes I prefer rechargeables, but I'd bring it on my next trip as a backup to a lower powered light.
L1D CE: the computerized gizmological successor to the L1p. I didn't like it at all, the overcomplex UI, the cheap construction, the cheesy switch. I sold it to another CPF'er who is delighted with it. If he's happy, I'm happy. It's very popular here so I guess it can't be bad objectively. I've simply developed relatively snooty tastes after being on CPF for so long, and the L1D CE just felt like a cheap gimmick to me. Of course that's very personal and subjective and if you find you like that type of light, then more power to you.
L0P (Seoul mod): bought this from Datiled this week and it's great. It's like the L0D CE with a better beam and with the computer crap removed. Just a simple one level twisty the way God intended
. Output is about the same as the L0D CE on high, but the hotspot and spill are both larger, and the transition between hotspot and spill is smoother. (However, the spill is dimmer). It's early yet but so far this is my new favorite, replacing the L0D CE as my EDC at least for a while.
All in all, Fenixes are good value-for-money lights that tend to be a little bit computer obsessed in some models, and with an annoying merchandising strategy of putting the best leds (currently RB100) only in the computerized lights. They are popular and hold their value, so if you buy one and don't like it, you can put it on BST and get back most of what you paid. I wish they'd make a 1AA version of the P1CE.