The link EMSLaw posted is very good and worth watching.
In my recent OR clinicals I spent time with an SRNA student and the Anestheiologist assigned to our cases. She swore by millers and said she only uses miller blades.
The doc on the other hand said he liked Mac better for adults and some kids, and miller only on very specific circumstances. But he preferred a mac+he recommended a mac to a new person.
Did either doctor show you their custom straight and curved blades?
Few Anesthesiologist will use "everyday" blades that we use in the field or even in the ICU or ED. If called to assist, they bring their own. The staff in the OR sterilizing department are also reminded every day about how much the blades cost. I must admit some are really nice but I would rather spend the budget on another piece of equipment for very difficult airways.
Once you understand where each blade is suppose to fit in the anatomy, you will understand why curved or straight is better. You will get to know if it visualization that may be the problem, for which the straight blade is better or if the tongue or jaw might be that problem and for that a curved blade might be better. Too many become accustomed to just sticking a blade in some manikin to see if they can pry the tongue away enough to see the hole and pass the class. Unfortunately many intubation manikins are not that realistic and it is difficult to say "do you see what anatomy your blade is not positioned by?" In the OR a good teaching Anesthesiologist will first initiate the intubation and hold the blade in place long enough for you to visual every landmark.
Laryngoscopes are reviewed in professional journals for Anesthesia and RT much like tools are reviewed in fine wood working magazines.
Example:
The McCoy laryngoscope in infants and children
http://springerlink.com/content/b51340k775770662/fulltext.pdf
Look at the reference section at the end of the above article and see how many articles have been written comparing the blades.
Good article about the various devices used in difficult airways. You may have to register to Medscape to pull these up but it is free and worth it.
The Difficult Airway in Adult Critical Care
http://www.medscape.com/viewarticle/578622
The Difficult Airway in Adult Critical Care.: Choice of Laryngoscope Blade
http://www.medscape.com/viewarticle/578622_14
Another good article from Medscape with case studies of very difficult intubations.
Use of the McGrath® Videolaryngoscope in the Management of Difficult and Failed Tracheal Intubation
http://www.medscape.com/viewarticle/574213
Here's a good comparison study:
Straight blades improve visualization of the larynx
while curved blades increase ease of intubation: a
comparison of the Macintosh, Miller, McCoy,
Belscope and Lee-Fiberview blades
http://springerlink.com/content/3n25gm726n5249j3/fulltext.pdf
Lower flange modification improves performance
of the Macintosh, but not the Miller laryngoscope
blade
http://springerlink.com/content/54r5581202488553/fulltext.pdf
The Cardiff paediatric laryngoscope blade: a comparison with the Miller size 1 and Macintosh size 2 laryngoscope blades
http://www3.interscience.wiley.com/journal/118744974/abstract?CRETRY=1&SRETRY=0
If you fail to understand when you are up against a difficult airway or just do repeated intubation attempts with the "try this and that blade until something works" mentality without fully understanding the advantages of assessing or the equipment, you will do damage. Thus, many hospitals are prepared with a difficult intubation cart with the expensive devices. However, it is very easy for those with poor training/education and a lack of understanding of the equipment and anatomy to turn a relatively simple intubation into a nightmare by traumatizing the soft tissues. Also, not knowing your limitations due to lack of medications to facilitate intubation. Even those that have an RSI protocol may find that the dosages allowed may only do a half-arsed job and medical control will have to be contacted in attempts to get the job done.
Even if you somehow manage to get the tube through the cords after a struggle, that patient may not be able to be extubated from the ventilator for many days due to swelling and some may require a trach. If the cords are badly damaged, the trach could be permanent. This is a rough time for a young college student who got intubated after drinking more than he/she should.
This is not an attempt to frighten one from intubation but rather to stress the importance of knowing the anatomy, assessing and anticipating the difficulty, the equipment and what your own limitations are. This may also help you determine if ETI or alternative means of ventilation might be appropriate especially after you have already poked around with the tube a couple of times.