Bad quality and they always skimp on something. I was a bit skeptical going with the Skyrocket over the One X because of the screen resolution difference but I did use an ion before the SR and in the end I actually don't GaF about that. The phone just works, I can rep the battery if that goes bad, it lasts over a day on moderate use on HSPA+, it has a good camera (once I Google up some Smartphone Photography 101 lessons

), it's fast, has an SD card slot ($20 for 16GB at Best Buy thank you very much) and it has all the social tie-ins I need. Upgraded to ICS a week after I got it, too.
A bigger, removeable battery. An SD Card Slot (those are too cheap now, omitting one is a disservice to your customers, IMO). A bigger battery.
HTC was known for 2-3 things leading up to the "Sensation/Raider" Series/One X:
1. Bad Cameras: With lots of noise, bad low light performance, and predictable white balance issues. Their earlier BSI sensors had excessive exposure compensation in lower lighting conditions (Vivid, Rezound - I haven't used a Sensation or MT4G or Amaze 4G to see how those perform in similar situations). Codec used for Videos was typically below Samsung/Apple, Sound Quality in Video was generally quite bad if not downright abysmal. They tended to compress their images more than Samsung and others as well.
2. Bad Screens: They hung on to the older LCD screen tech for WAY too long.
3. Low Internal Storage - Not until the Vivid/Amaze4G/Rezound did they give a respectable amount of internal storage in their devices. Remember the G2 storage debacle.
4. Volatile Build Quality (Z Hinge, Materials, Thickness, No Gorilla Glass, Excessively protruding camera modules that scratched easily when phone on back or cracked easily if dropped on back, weightiness (this and thickness is an issue for people who prefer cases like Otterboxes), etc.). Their counter to the Samsung GS2 on AT&T and Verizon was the Vivid and Rezound, for example, and the Amaze 4G on T-Mobile (though I rather liked the look of the phone, and it's camera buttons).
5. Small Batteries: 1230 mAh when everyone else was using ~1500 mAh batteries. 1620-1735 when everyone else is using 1850-2100 mAh batteries on similarly or better spec'd (in the case of devices with AMOLED screens, even more EFFICIENTLY spec'd devices). I'm glaringly omitting things like BT 2.1 when Samsung starting using 3.0 back in the GS3, which can have huge implications on battery life for people who use BT Headsets/Headphones, in car, etc.).
6. Tech Lagging: WiFi Direct, NFC, etc. all came later to HTC handsets than same-generation Samsung handsets.
Plain and simple, most people didn't really like HTC's devices all that much. They liked HTC Sense, but even that became a beast - and they liked HTC's support of the dev community (things turned quickly when they started locking bootloaders - people jumped ship to Samsung in droves). TW3/GS1 was so absolutely terrible (RFS, Lag, borderline InPp GPS, PenTile screen with Image Retention, constant force closures/black screens due to buggy TouchWiz, absolutely terrible updates especially for US variants, etc.) that HTC could have steamrolled Samsung if they wanted, but they choked, and Samsung's Marketing distortion field was enough to bury HTC, because HTC's devices simply weren't that good, anyways.
The One Series are good phones, but they took shortcuts that simply look bad especially when OEMs like Samsung take things to the next level (not only do you get an SD card slot, but you can use... OMGZ... 64GB cards!!! Yay! - not only is the battery removeable, but it's... OMG... 21% bigger than the One X's battery). These things do matter, because a lot of people buy with possibilities in mind, not just the here and now. What you can possibly do with a device often means a lot more than we thing. This works in a lot of markets, like automobiles. Someone may never have to tow an R.V., but they'll get a truck that can do it simply because it can.
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It's either bloated or it doesn't have enough features but you can't say it's too bloated AND not bloated enough in the same sentence.
Yes you can. Being bloated and being feature packed aren't the same thing. I can write a bloated Hello World program, no problem, and a streamlined one. Neither has more features than the other. One is just coded worse than the other.
Sense IS bloated and it is heavy. It's been a constant complaint about it for quite a while.
TouchWiz was absolutely terrible at 3.0 and the Original Galaxy S was super bad for such a hyped Flagship and HTC let that opportunity slip between their fingers cause they had a few good quarters and wanted to milk the cow with 500 different smartphone models.
Didn't work out too well.
As for memory, HTC has generally been good about RAM. They actually moved from 512 to 768 eariler than I think any other Manufacturer. The problem they've had has been with actual Storage on their devices. They didn't give much at all.