Compared to other bikes in its segment (CBZ, Pulsar etc), TVS Fiero has following shortcomings:
No laxury of 5 speed gears.
Tyres are not wide enough.
No foot rest shield on silencer.
Further, disc brakes and Electric start are offered additionally and not as standard fittment, which adds to cost.
If you plan some modification to your bike, I do not recommend Fiero, Because, with modifications (Replacement of tyres, silencer, headlamps etc), fiero looks awkward and it also effects the performance of the vehicle. One should enjoy the byke as it is.
Fuel tank capacity can be increased to 15-16 litres (13 @ present) without harming the overall look.
Milage is quite effecient (56+/- 3 kmpl on city roads as against 70 kmpl under test conditions as company claims) compared to other vehicles in its segment. Quite cost effective as well in terms of maintanace and performance.
Finally I recomment fireo if you can ignore its shortcomings, given that its overall performance is worth considering. Wait for improved versions if you can.