I was at Bronner's Christmas Wonderland the other day (Frankenmuth Michigan)
As I drove up, I saw that almost all of the outside display has been converted to LED lighting.
Horrible vivid blues and whites are the worst. I do not like LED Christmas lights. I went to Bronner's to get
replacement flashing C9 and C7 bulbs. Thankfully, they still sell real Christmas lights. I have tried to like them, LED's would
save me on my power bill but I just think they look bad. For this year, I have 3 strings on random flashing transparent C7's around the front of my house with a string of random flashing transparent C9's in the bushes. Runs 550 watts from 4pm-11pm. Next year I think I am going to do Ceramic style C9's all the way around. I think it is a relatively small price to pay to keep the childhood memories and look alive. I have a large collection of Incandescent mini lights as well as C7's and C9's I think I will be able to continue to use real lights for the foreseeable future.

Static

I see alot of LED light poping up everyware here too I have them as well outside running from 4pm 10pm I use them because I can not afford to run the classic C9 and C7s but I have a couple of C9 stings in my room that stays up yearround.

Apart from real candles, nothing beats incandescent christmas lights. IMO, the blue, whitish-yellowish and daylight white LED are  YUCK.

Well, if someone want to save electric bill on decoration lights, why to not use them at all? That will save 100% of their power input...

IMHO This is one of the best uses for LEDs out there. I do prefer LED string lights

I was more pointing to the use of "energy efficiency" as an argument to select such short time use decoration lights...

LEDs have few clear advantages here :

Vivid colors esp. cold ones

Low heat dissipation - safe to be in contact with flammable decorations

Low load - can connect lots of them without overloading wiring and extension cables

Less breakable

Less prone to rush failure modes than series incandescents with EOL shunts

Long life

And thats before counting in energy efficiency directly

Ash:  I agree with everything you said about LED Christmas lights but I think the fact that they are so vivid is the main reason that i don't like them. If I could find some that looked more like the older incandescent c7's and c9's then I would buy them. I don't care for the faceted versions but I did see some smooth LED c7's that had a decent look to them but with only one little LED, they were dim compared to the real thing. I hope they come out with something in the future that retains the look of incandescent lights. The other thing is they need to get the price down on the LED lights. Bronner's wanted $44 for a box of 25 c7 LED bulbs to retrofit a string vs $6 for a box of 25 incandescent bulbs. I guess for now I will just pay the price for using power hungry lights. I do most of the time anyway because all the vintage fluorescent stuff I collect tends to use a lot of power but I like the T17 size and the blinky look of preheat.

@Ash: What you describe is valid (I mean what is related to safety), but only if the decoration is build using sealed LEDs, operatig at SELV. But not anymore for LED retrofit lamps.
The vacuum incandescents of such low power are by far not running so hot to be dangerous for nearby things, neither sensitive for splashing water.
The heat from them is significant safety factor in the setup: It keep their socket dry, so the risk of electric shock low. Although the design should not rely on it, it become significant after some years of use, when the seals deteriorate.
And that is the reason, why LED's have to be supplied by the SELV: They output no heat, so the water stay there and create conductive bridges between live conductors and the surface. And then the only thing really preventing the electric shock is the safe low voltage.
But with the SELV the currents become the same as on the mains incandescents (if you want to keep the brightness), requiring thicker wires again.

The colors are an individual preference, there is no means to comment on it...

With incandescents there is the extra problem with breakage and then exposed filament (can ignite) or live conductors (can touch something unrelated and begin arcing / reistive heating / electrolysis)

Also the series incandescents with the EOL shunts. If few lamps burn, the remaining can posibly go in a rush, and i think the last ones might even explode - again causing the same problem

With the heat baing the protection - Did not think of it that way (its actually the same as what is happening with my floodlight). Most LED chains sold here are series on mains voltage and even have 50 HZ flicker. Some of them are potted with epoxy, and some are just shrink wrap but they appear to hold up fine

A city in the region installed lots of them everywhere few years ago (tens of them nested between poles, wrapped on trees, ....) and they were powered for many months by now (they use them for just few months in a year) but left installed for all the time, and most of them are still working ok. They have 2008 ones that hold up well, and 2006 ones which are the shrink wrap type which are slowly but steadily failing. All are the series type with just resistor and lots of LEDs across 240V

Static1701, I am with you on this one!  I prefer the old fashion C7 and C9 twinkle bulbs.  I do like LED also, but the big old fashioned C7 and C9s will always be my favorite.  They are plentiful on E-Bay also.

We have gone LED on most of our Christmas light display (about 3,000 lights and up)

We only buy the warm white LED's for the display as the cool white are too flickery and cold looking. The warm white's are very nice looking. Yes, incandescent would be great, but we can not afford it. The switch to now about 70% LED has saved us alot of money. Plus, now I can add alot more lights to the one dedicated 15a circuit I have.

LED's are great for the trees because the wind doesn't break them. The incadescents had to be fixed every week due to wind and snow.

LED coloured lights are ok if their put up and not disturbed.
I used to have 2 sets on the outside of the house at christmas, and granted, they looked good at night, but I used to take them down, wrap them up, and the following December, get them out again.

Now heres the interesting bit, doing this they only lasted 3 years!, and if you consider they only run for 6 hours a night, JUST in the month of December, then they only lasted less than 3 months.
The only thing is, most festive lights in the UK are now LED!

Put mine up yesterday ( still in the little tree, all went into the box for storage) and the incandescents flashing string is still working, 5 years after I bought it. I see plenty of the LED strings around, and plenty of incandescent ones as well. Sad thing is that they have a similar life.

LinearSLI/H - What failure happened to the LED string ?