The last time a character was reincarnated in a game I was running, I had a long chat with the player about their expectations and concerns. While in the old days, having your character transmogrified against your will was common, some people react badly to it, and when you consider that, for a very long time, coming back from the dead was already penalized, usually led to more insult than injury.
I had a Fighter in 3e who died sacrificing themselves to save their allies against a vampire. The party Druid offered up reincarnation as an option. Losing a level already felt like a punishment to me, since I also didn't get any xp from the battle I won, but I put my faith in the DM to maybe balance things out down the road.
Oh what a fool I was. The DM rolled the dice, chuckled, and told me that my Human Fighter was now a Gnome. I lost two points of Strength, could no longer wear my (medium-sized) armor, and had to give up my shield +3 in order to wield my axe in two hands. My movement speed was tanked (20 ft. base speed reduced by heavy armor), my AC drastically lowered (even with the +1 size bonus), and I became the butt of jokes. I was pretty miserable about it, though in retrospect, this was more to do with the fact that I was no longer happy being a Fighter. It seemed like at every turn, the DM, as new to 3e as I was, was constantly complaining about my AC, attack bonuses, and damage all being "too good" because his monsters kept dying "too fast".
I eventually got my humanity back, but I would have been better off, I think, retiring happily and asking to play a new character.