This is a bit late, but here is Ruth's assessment:

http://www.operatoday.com/content/2008/04/anna_bolena_eng.php

I went on my own, and I was entranced.  I realise it is not everyone's cuppa, but if you are going to do it, this was fine.  I was under the impression that you could only really get bel canto at ROH, and here it was within walking distance of my home.

What made it possible was singing it in Italian with a tenor with a Romance mother tongue.  Actually Luciano Botelho was Brasilian, and I suspect Portugese is a lousy language for singing (all those nasal vowels) but the contrast with Barry Banks at Lucia at the ENO was staggering.  I felt I had always made allowances for English tenors singing Italian, but here was a convincing Italian sound.  See Ruth's perceptive comments.  Also, he was neither shorter than the prima donna, nor noticably overweight.

The surtitles were exceptionallly crummy.  Reminded me of those things in London bus stops which say "Bus now due" for five minutes

English Touring Opera are still touring until the end of May if you are interested.

http://www.englishtouringopera.org.uk/tourdiary.php

The Hackney Empire is sweet.

When BAL did the complete recordings of Callas about 10 years ago they recommended her Anna Bolena as her best piece.

I duly bought a bargain version, where it languished some time.  On the ipod, I managed to download the tenor's final aria (cut for Callas - after all, who wants to hear the tenor) and got the Ramey duet from Act 1 on a disc of Samuel Ramey Sings.  By changing the track numbers on itunes, I now have the Callas recording (hiss, crackle) with the Ramey duet in Act 1 and the late Jerry Hadley in his final Act 2 aria.

The desperately sad thing about the Tower Of London production was that it was scuppered by external elements,  almost all of them attributable to the location of the performance-space.  The show was strongly-cast and - when audible - well-performed.  It was not the fault of those involved that the orchestra was hidden under the stage and boxed-around so that they were inaudible, nor that aircraft went overhead at 20-minute intervals, nor that only the three main principals had voice-mikes, nor that police-cars from Tower Hill Nick blazed-past with sirens every 10 minutes.  Nor even that the scenery all blew away in Act I, that seagull landed on-stage and walked-around (finally being chased-away by Cardinal Wolsey), or that torrential rain obscured most of the second half.  Hence my advice to our own Lord Byron, who had plans to stage open-air opera in London parks...  avoid open-air venues like the plague.   I felt sorry for the cast & conductor, who gave of their very best in woeful circumstances.  Opera isn't a Renaissance Fayre, and needs a different set-up to be given a fair chance