I have an LF2 and an LF5. Both pack a lot of features and performance into a well made and functional light.
I admit that I had to tinker with my LF2 switch as an Energizer lithium cell appears to be just a hair too long so I had to add a brass washer shim over the switch to add a bit of length. Alkalines seem OK so it literally is fractions of a millimeter. Still it is a very good keychain light, nice size, good anodize finish, good build quality and a great beam (SSC) for that type of light. I bought mine used so I haven't bothered trying to get any sort of service due to the switch issue as it works perfectly with the brass washer. AFAIK I haven't heard this problem from anyone else, but it may be a factor of others using NiMHs or 10440s in theirs (my next purchase will either be a Costco Eneloops pack or AW's 10440/Nano deal).
The LF5 has been rock solid and I run it on 14500s and it works great.
I really like that I have the option to choose the levels, but that it works just fine as a 2 stage (3rd level optional) twisty light without any other programming or effort straight out of the box - really no more difficult than a Fenix and really more intuitive and easier. I can't emphasize this point enough as I agree that the UI seems to be a stumbling block for many. You can use it like any other two stage twisty (like the Orb or CR2 Ion or many McGizmos) right out of the box.
What you get is the option to use the third user adjustable mode (easily accessible with a double "switch" to toggle it to that mode, single "switch" to toggle back to standard mode) and to change the default first and second levels you reach from twisting from the IIRC 15% and 50% factory defaults - including a very low low which many have clamored for. Every feature, whether it is strobe, SOS, overdischarge protection, voltage indicator, programming mode, etc... is tucked away some number of "switches" away and can be completely ignored if you desire. And while programming is a bit of an effort to do, I don't think it is anymoreseo than the HDS EDC lights were other than the positive "click" you got from a tailswitch rather than the silent twist. Once you set your levels, if you want to do so, you can again leave it alone. For most users you aren't going to have to do a bunch of twists on a daily basis. And there is a factory default reset feature if for some reason you get lost - another well conceived feature. And of programmable lights, how many other than either the Surefire Titan/U2 or VB-16/Proton style one level adjusted by a ring/buttons is really that intuitive? By nature with a switch or twisty there are only so many choices in terms of how to access advanced features - read the new Arc LS manual of arms to see what a year plus of thought get you - not the riddle of the Sphynx exactly but not really intuitive either.
I do think that a few opt for other lights despite the rich feature set of the Liteflux lights not only due to a concern (not necessarily justified IMHO) of the UI, but for the absence of a US based dealer, and also for some slight performance advantages of some other lights, particularly the Fenix. The Liteflux is a very capable light, particularly on NiMH and Li-ion cells for which it really seems to be designed, but in 'shootouts" with other AA based lights for example there are some others that are slightly more efficient and give slightly more output - again mostly Fenix which does appear to have a really efficient driver but a much more limited set of options. The Liteflux still seems to be about the best combination of programming features and performance that does not have HDS/Novatac stamped on the barrel.
Also if you use low-low mode, it's still useful once you're eyes have adjusted and will last for 10+days (compared to ~8 hours on low for the fenix). 
