I really like the R8 (especially the V10) but consider when the NSX came out, it targeted Ferraris 348 and with slightly less power, equalled or exceeded it in pretty much every category. Then with the 3.2 it put up a good fight compared to the 355. It was also over 2 seconds faster than an M3 to 60 with 40% more power.
The V8 R8 has the same power as a modern M3 and is actually slower to 60 than those equipped with DCT (including my Sedan).
Subjectively i like the looks of the R8 and its a great DD but while 420hp is nothing to be ashamed of, the V8 is more on the lines of a early 90s 200hp MR2 Turbo than a 270hp NSX. The V10 is probably a more comparable "modern" nsx but its not as competitive against a 458 or 12C like the NSX was to the 348.
Personally I'd pick a 12C as a DD or a 458 as a weekend toy (or maybe even a DD) over a V10 R8. I still like the R8, but its not going to go down in history like an NSX, 12C or 458.