Theres nothing wrong with the Mk1 1.8 RSi and I dont think many people would slate it. Its a nice high-spec car with enough poke to take it from 0-60 in 8.5 secs and on to 120mph. In my opinion, its a better crusier than the 16v due to having its torque at lower revs and its a softer riding car.
Its bound to live in the shadow of the 16v and the Williams becuase theyre the hot hatches of the range - and people like the hottest cars. They were developed by Renault Sport and used in Group A rallying; the RSi was the top of the Renault-developed range.
The RSi is a good hatch, though its still got the looks and much of the mechnicals of the rest of the Clio range, except for the spoiler and skirts. The 16v and Willy get all different panels except for the doors and the boot, different suspension system (four torsion bars instead of two), wider tracks, different clocks/gauges/interior, uprated cooling/transmission/brakes...and loads of other things that I forget right now!
The performance of the RSi is very respectable - not far off the 16v/Willy, and gap is closer than say between the Clio 2 RSi (also called "16v" and "1.6 Dynamique") and the 172/Cup. Itll never have the revviness of the 16v or the sheer flexibility of the Willy, but its close. Sadly, I guess itll still have bills of the 16v/Willy.
I dont think anyone here seriously reckons the RSi is a duff car - were all into sporty Clios. I guess you might have thought they get a bit of stick when people ask if they should get a 16v or an RSi.