What's wrong with Thiel?

You must learn to take a lot of information with a grain of salt. Everyone has an opinion about everything. My best advice is to listen and judge for yourself if a particular speaker or whatever is good for YOU.
As for your original question, I don't think anything is wrong with Thiel speakers. They are time aligned and phase correct. A lot of thought and engineering has gone into the design. I have never owned Thiels but have listened to them many times. I settled on Vandersteen for my on personal reasons. They are also phase correct and time aligned. Thiels are well made speakers. Jim Thiel uses his own designs and does not source drivers from other sources. they must be set up correctly and are generally in need of good amplification.
I have tried many cables of all prices and finally settled on Harmonic Technology Pro Silway MK.II. Here again you need to try and Harmonic gives you a 30 day trial at which time you can return the cables for a refund from your dealer. For a silver cable, they sure are smooth without loss of detail. I personally like them better than the Nordost SPM line. The Silway retails for $399/1 meter or $250 for 1/2 meter. Not bad considering the performance.
I also like the Tara Labs ISM The 2. They are also very smooth and detailed. The 2 is more neutral than the cheaper Air 1 series. However, The 2 is a bit pricey as in $1395 for .6 meter.

I agree with Bigtree. Nothing is wrong with Thiel they are very good speakers, well designed and built. They do need good amplification to get the most out of them. I have a pair of 3.6's and utilize Conrad Johnson electronics and audioquest cables. I love the Thiel / CJ combination the Thiels are very accurate and detail. The only speaker I thought about replacing them with are 7.2's. I would highly recommend Thiel speakers. Dunlavy also makes an outstanding speaker although I have no personnel experience with them.

I'll respond since I have made some remarks about Thiel speakers here on Audiogon that could be misconstrued or misinterpreted as being negative or somehow disparaging.

There is absolutely nothing "wrong" with Thiel speakers. They sound very good if used within the proper parameters. As Bigtee states they are phase and time coherent and that is a wonderful thing, but they are designed to be listened to from a particular distrance and they will sound considerably better at that distance because that is the distance at which the sound will arrive "in phase" at your ears. As a general rule Thiel speakers are designed to be phase coherent for a larger listening room, i.e. a longer distance from the speakers, than many customers assume. I am sure Jim Thiel would be more than happy to walk you through the setup of your speakers. Jim is a very intelligent engineer and has contributed a lot to our industry, and his company is great to work with both from a consumer's and a dealer's perspective (I am not a Thiel dealer but know Thiel dealers who say Jim is a class act through and through)

The other important consideration is amplification - and this is where my remarks have been directed recently in these forums. There is nothing "wrong" with Thiel speakers so long as you run them on a sufficiently capable amplifier. Thiel's are very difficult to drive because their impedance is generally quite low. This means that tubes are pretty much out of the question. They simply will not be able to keep up with the current demands, and the sound will suffer considerably as a result.. But you cannot arbitrarily select a solid state amplifier for Thiel's either. The amp must have high current output and must be comfortable with extremely low impedance levels (2 ohms, ideally lower) Amplifiers that make use of current limiting circuitry or that do not play nice with loads under 4 ohms are poor choices. Again, I am sure Jim Thiel would be more than happy to advise you in this matter. I have never heard of a customer calling Thiel and receiving misleading information in the interest of closing the sale. He will tell you the truth and tell you whether or not your room is big enough or your amp is capable of driving his speakers.

If you set them up properly and use the right amp, Thiel's can be magical. But they are tricker to incorporate into one's system than some other speakers which have less onerous demands on the amplifier and don not require such a large listening room.

The response from Symphony Sound is "on the mark". The biggest issue with Thiel speakers is finding a compatible amplifier, due to the impedance curve of the speakers. You should also try to audition the Thiel's and compare them with several other time-aligned and phase-accurate speakers, such as Vandersteen and Dunlavy.

Richard Hardesty has written fairly extensively about the Thiel speakers in one issue of his online audio publication, "The Audio Perfectionist". If you will contact me by private E-mail, I will forward Hardesty's extracted comments to you.