I looked at this long time ago... If I remember correctly, after 6 Kf1!! Black is pretty much bust, but this is from memory, I could be wrong...
Traxler discussion

My manuscript also recommends Qh4 against Ke3?!. I'll have to look up whether it gives Gonnosuke's line specifically.
Another interesting line is Nxe4 instead of Bc5:
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Nxe4
It may work against someone who has never seen it before.

I remember starting out that I used to love to play the fried liver attack every chance I got and won quite often with it and didnt have to play any endings, win or lose ! However, a strong A player in our club introduced me to the traxler by crushing me from the black side several times and from that point I started playing the max lange instead !
Here are two very useful links on the Traxler:
Five articles on the Traxler by Maarten de Zeeuw (plus some analysis by some other guy)
An article on the Traxler by Stefan Bücker
Bucker agrees with (and elaborates on) Gonnosuke.
I love to play this as black, but the Bxf7 and Bb3 always leave me a little akward and the Nxf7 Kf1 lines are really way over my head.

I bet one could write up a primer on the Traxler, where studying it for a couple of hours gets you to a level where you can beat, from the black side, anybody who hasn't studied it.
Unless white wimps out and castles, but then it's just a regular game where black should be a little better because of white's loss of two tempi.

Well, here is a cool game using the Traxler Variation:
http://www.chess.com/article/view/take-the-queen-see-if-i-care
ADK
I like to play this, and wish I got more blitz games with it (although I don't have the guts to play it in OTB tournaments ). Really, what worries me is when my opponent plays Bxf7+. Against Ke3, I think both Qh4 and Qe7 (threatening Qc5+) are OK, although I don't know the lines in that very well. Against Kf1, necessary is Qe7 Nxh8 d5 exd5 but after exd5 Black seems OK after both Nd4 and Bg4 (pvmike gave a sample line that you can look at).
Here's a good game to look at to see how to play against Bxf7+. http://www.chessgames.com/perl/chessgame?gid=1018213 where Beliavsky uses the Traxler to beat his opponent, who is no less than current world champion Viswanathan Anand.
This is the debut of the Traxler, showing why Ke2 is bad. It does naturally look bad, but I do think you actually have to know a line or two. http://www.chessgames.com/perl/chessgame?gid=1224609
There are a lot of other cool games in this. So far, I haven't seen anything that looks like a certain refutation, although of course some positions are unclear.

The Traxler is a very complex opening, but probably isn't worth the trouble. Unless you are a scholastic player who faces the Fried Liver Attack on a regular basis, the hours you put into pouring over the complications aren't going to do you any good.

My manuscript also recommends Qh4 against Ke3?!. I'll have to look up whether it gives Gonnosuke's line specifically.
Another interesting line is Nxe4 instead of Bc5:
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Nxe4
It may work against someone who has never seen it before.
Well, I have a line that busts black with the Nxe4 variation.
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Nxe4 5.Bxf7+ Ke7 6.d4 h6 (6...d5 7.Nc3!) 7.Nxe4 Kxf7 8.dxe5 Qe8 9.f4!

I play the traxler every chance I get, and since I play the two knights defense every chance I get, the traxler pops it's lovely head quite often.
Sir David, that's a great game, Anand-Beliavsky. Beliavsky has certainly got a lot of chutzpah!

My manuscript also recommends Qh4 against Ke3?!. I'll have to look up whether it gives Gonnosuke's line specifically.
Another interesting line is Nxe4 instead of Bc5:
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Nxe4
It may work against someone who has never seen it before.
Well, I have a line that busts black with the Nxe4 variation.
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Nxe4 5.Bxf7+ Ke7 6.d4 h6 (6...d5 7.Nc3!) 7.Nxe4 Kxf7 8.dxe5 Qe8 9.f4!
I have 6...h6 7.Nxe4 Kxf7 8.d5 Ne7 9.Qh5+ g6 10.Qxe5 Bg7 11.Qf4+ Kg8 12.Nbc3 "White has an extra pawn and a superior position, as Bilguer's 'Handbuch' noted as early as 1916." (Estrin, p.9)

I also play TRAXLER whenever I have the chance and I have to say that I never lost in this opening.
I even managed to beat a NM in an OTB 2 hours game tournament. Only 15 moves and he resigned.
1 e4 e5
2 Nf3 Nc6
3 Bc5 Nf6
4 Ng5 Bc5
5 Nxf7 Bxf2
6 Kf1 Qe7
7 Nxh8 D5
8 Exd5 Bg4
9 Be2 Bxe2
10 Qxe2 Nd4
11 Qxf2 0-0-0
12 Na3 first move out of my theory. ( he already used about 45 min)
12 ... Rxh8
13 c3 Rf8
14 Kg1 Rg4
15 Qe1 Qc5
Although he was a NM he never saw this line but he played it quite well. After some analisis after the game I saw that 14 Ke1 would have given him a better position.

Well, I have an improvement for white in the 7.Ke3 variation
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kxf2 Nxe4+ 7.Ke3 Qh4 8.g3 Nxg3 9.hxg3 Qd4+ 10.Kf3 d5 11.Rh4 e4+ 12.Kg2 0-0 13.Nc3!
Ball is back in black's court.

To start, I will put forth one line for testing
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kxf2 Nxe4+ 7.Ke3!?
7...Qh4 8.g3 Nxg3 9.hxg3 Qd4+ 10.Kf3 d5 11.Rh4 e4+ 12.Kg2 O-O 13.Bb3
Rxf7 14.Qg1 Qe5 15.Nc3 g5! =
I have an improvement to be considered.
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kxf2 Nxe4+ 7.Ke3 Qh4 8.g3 Nxg3 9.hxg3 Qd4+ 10.Kf3 d5 11.Rh4 e4+ 12.Kg2 0-0 13.Bb3 Rxf7 14.Rf4 Rxf4 15.gxf4 Be6 16.Nc3

I'll see in my manuscript what they say about this line. So your improvement is on move 14 then, with 14.Rf4 instead of 14.Qg1

After 6.Kf1 black is still okay, I think, but in this line it seems like black at least draws.
I think it is time for a Traxler thread. Anybody play the Traxler?
I am wondering if we can test our theory lines against each other in the Nxf7 variation in the Traxler (1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7).
Can white acheive an advantage in this variation?
To start, I will put forth one line for testing
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kxf2 Nxe4+ 7.Ke3!?
Feel free to post other variations for the community to discuss.
Time to have a theoretical battle with our novelty weapons.