i took it for about 14 mths for svt ,and i found it to be ok ,there are better ones for svt ,like neiblet{nebivolol} which is a more selective for the heart ,but inderal is known to be good for migraine as well...for the first few weeks just watch standing up quick and things like that ,it is better started on a low dose and moved up as needed,,but apart from that it seems to be well tolerated by most.
I took it on/off for about 12 years, and can still take it "as needed" if my palps act up. I was tired when I first started taking it, but that wore off and I was fine.
My daughter took it for migraines and it was wonderful!!