I personally big fun of Yaks and Yak-3 in particular.
Yak-3 is "ultimate" fighter: small, nimble, good diver, climber, decent speed and amazing FOV.
I love the central concentrated gun package, it has the firepower that is "good enough" also you can't spray and prey with it.
But it has major drawbacks: pathetic loiter time (which requires you almost always to throttle back to save fuel at MA) and even more pathetic ammo load. It is also catches fire easily (but not as easy as Japanese paper planes)
Of course there are better planes. The hardest plane for me in Yak-3 to deal with is Spit-8/16... these are "Easy mode" planes as they better TnBs and have very comparable performance in the rest parameters like speed, dive, climb etc.
Finally... Yak-3 is considered one of the best WW2 fighters...
In general I always prefer Yaks over Land-Lease planes in Eastern Front setups.