Personally I like the M8. The biggest drawback of the M8 and I don't believe anyone touched on it, is the battery tray problem. Everyone and their brother has a problem with the 3-pin connector on the battery tray getting very loose and causing intermittent contact. A small piece of foam between the battery tray and the retainer usually solves this problem, however in some cases I have seen it as very severe.
The M8 is getting cheaper and cheaper to pick up deals on used. For example I just grabbed another M8 off eBay, with a carry bag, instruction manual, extra rx & rechargeables for $155! There may be better radios out there techincally speaking, but most people cannot even use the options and adjustability of the M8, so why spend more on even more gadgets when the venerable M8 will still do the job?