I suppose it depends what you want to see and do.
I love Symi as does my wife, Gail.
But, it does depend on you as people - and what you want to see/do. For us, Symi is a total delight. I feel sure that you will get good information and help here.
And, because of the proximity of Symi to Rodos(Rhodes) you will have a great gateway to the rest of the Dodecanese, the Cycladic Islands ........ well, what you want is there.
The only bit of advice - and this is appropriate for anywhere - is that YOU must visit and decide. Recommended accommodation, tavernas, bars etc., etc.. are a matter of personal taste. What is one man's meat is another man's poison !
On Symi - as other places ( but unlike some resorts in Greece that cater for the 18 to Idiot) - it is all great .... never come across a taverna/estoratio/bar that I wouldn't re-visit .........not one !
Giallos can be a touch busy when the day boats from Rhodes are in port, and can be a little "Precious" at certain times of the year, but otherwise, right on the money!
Chorio, Pedi, Nimborio - just fine ( timing, my boy, timing).
Just go, accept that it is what it is - and above all, relax and let the island take away the troubles of the world. And - if you are not "moved" by the sight of Giallos as the boat turns into the harbour as dusk falls - you have no soul !!!!!!!
A tip - as the boat approaches Symi, go up on the highest viewpoint of your boat. As your possible disillusionment at the slightly barren island makes you wonder what you've done, the delight of seeing the harbour kicks sense into you ! Please .... relax and enoy it all.
It's a personal thing ...... there are better parts of Greece ( but not many and hard to find) and there are worse ( easier to find !)
But Symi - especially at dusk looking at the harbour from say, the Haritomeni restaurant roof terrace, priceless!
Enjoy it all !