Not at all. They do sit you higher off the ground, so if you have short legs, you may have to get used to not being able to flat foot both feet at stops.
The FJR is considerably more powerful than a stock cruiser, but it is totally docile so long as you don't get silly with your throttle hand.
Comfort wise, I didn't find the stock FJR very good.
The windscreen was too little and aerodynamically poorly designed. I bought a V-stream for mine that is phenomenally good.
The handlebars are too sporty for a bike with a windscreen (no airblast in the chest to take the weight off your wrists). I put a set of Helibars on and they too are fantastic. Inline engines are inherently buzzy. The mass of the Helibars along with some weighted bar ends all but eliminate that too. Also, the right bar end also acts as a throttle lock.
The footpegs give you a one position choice for your legs. I put a set of highway pegs on mine.
The suspension wasn't that compliant, but very stiff. I put Hyperpro springs in the forks and $1000 Hyperpro rear shock on it. Very competent now.
The centerstand lift was in the way when I'd put my toes on the pegs during aggressive cornering. I ended up having to saw it down and reapply the foot pad with JB weld. It's held up just fine after several years, though it does require a little more effort to get it up on the centerstand now.
The stock seat was alright, but I put a Corbin on mine because it is much smoother when making side to side transitions on the bike when riding the twisties.
The fueling on my year model was not too good and resulted in jerkiness during on/off throttle application. I added a Power Commander to smooth that out. It had the side benefit of giving it a much stronger feel in the meat of the powerband.
The trunk they sell for it was junk. Mine broke off with nothing in it with only about 1000 miles on the bike. I put a Givi on mine and never had another problem.
But are they great bikes, yeah, they're pretty fun: