I've grown a lot of nirvana strains and no they don't all taste like lemons, not even close. My first purchase was top 44 which is now discontinued. I haven't grown any nirvana seeds since 2009 and I plan on running their pure power plant again in hopes of finding a pheno I once had.
You don't always find a keeper in their 10 packs but I have found 3 or 4 really great phenos.
My stop 3 strains
Top44 - killer fast berry/fruity flavored bud, nice and potent.
Ice - heavy flower, real potent, tropical fruity flavor, very vigorous
Pure power plant - densest bud I've ever grown, vigorous, potent and a unique honeycombs flavor
I've grown
swiss miss - discontinued for swiss cheese
snow white
bubblicious
ak-48
blue mystic
crystal
k2 - discontinued
And probably more but it has been a while. Most of the strains were close to descriptions, blue mystic had hints of berry smells, bubblelicious had hints of bubble gum. The ones that didn't make keepers were basically because they were up against better phenos of other plants I ran with them. If on a budget they are great.