Well, no offense but i feel 6233 is overall much better product than the 6300...the cam module is better than the 6300 as it takes better, more natural pics (as already compared at many review sites)...
6233 allows very good quality vga video recording...the 6300 only manages qcif resolution video recording...
6233 has awesome loudspeakers comparable only with the n73!! N though u may not use loudspeakers in trains n buses, as i agree, it looks cheapo, better loudspeakers mean, u do not miss a call in any circumstances!!
And finally, 6233's battery back up is very very good as it comes with a 1100 mah battery while the 6300 has only a 860 mah battery!! Battery back up is the biggest issue with the 6300...!
Rest, both the phones are identical s40s....ohh n i forgot, 6233 is 3g while the 6300 is not...
Though tht hardly matters, but the above points definitely go in favor of the 6233...