Could anyone who has played a Samurai using the Bloodlust sword tell me if you still get critical hits and or lightning strikes? or does the beserk attack mode of the sword cancel out one or both of these?

You won't lose any of the Samurai abilities with Bloodlust. You'll still have chances of critical hits and Lightning Strikes.

heh, Bloodlust...i usually leave that one alone, but sometimes...I would say for a Sam, Bushido and BL are about equal, only because you can also use a Bow readily with the former. And BL soaks up Stamina.
Muramasa or Light, though...
Have fun!

I used bloodlust with samurai until he was 20th level and switched to light sword. Bloodlust is an awesome weapon with the problem that you may have considerable accuracy problems until your skills and stats can compensate. You may want to take an ankh of dex or just use one weapon for a while.