I kept wanting to be a thri-kreen PC in 3.x, but I needed to be in a fairly high-level campaign to do so. In better-suited campaigns (eg one that went from 1st to 13th level) thri-kreen did not fit the setting
It only happened once, and I made the mistake of telling the other players, and they all decided to be monsters. As a thri-kreen, my PC barely understood the concept of money, the warforged PC was likewise (there's no Eberron fluff to support this, btw) and the wereape was the face of the party. There were only three of us (second mistake; only use a weird character once all roles are filled), we were trying to playtest Book of Nine Swords (third mistake; use normal classes for monsters; that's one I avoided by just playing a ranger, but that meant I wasn't stress-testing the system; oh, and the wereape had to give up 5 class levels so had only one level to play with, making stress-testing impossible) and maybe a few more.
And
then the wereape, who was playing some class with a Healing Strike-like ability,
refused to use it. It wasn't costing him actions, so what gave? In our first encounter, we slaughtered the opposition. In the second, it slaughtered me in the first round, dropping me to six hit points, and the wereape refused to use healing.
Too bad. I've practically memorized
Thri-kreen of Athas too. In my 4e campaign we have a thri-kreen, but they lost so many abilities (like the venomous bite, or even at-will claw attacks) that they've lost a
ton of flavor. 4e is probably too mechanically tight to do a thri-kreen PC justice, but I can still make kick-ass thri-kreen NPCs. (I haven't
used these guys yet, though.)
In 4e I once allowed a PC to be a bugbear. Oversized weapons is overpowered. My advice is to say no.